SCIENCE OBJECTIVES AND GIVE SCIENTIFIC REASONS


Q.I (A) Fill in the blanks :
1. The horizontal rows in the periodic table are ................ .
2. From left to right, the atomic size of an atom................. .
3. There are ............... periods in the periodic table.
4. An element is placed in group II A, so the number of valence electrons is  ..............
5. An element is placed in 2nd period, so it has ....................... shells.
6. Noble gases have valency as ....................... 7. Metals have a tendency to ....................... electrons..
8. Valency across a period ....................... .
9. Valency down the group ....................... .
10. Elements of group I A and II A are ....................... .
11. An atom is said to be a non-metal if it .................... electrons.
12. ....................... is the only element in duplet state.
13. The electronic configuration of Neon is ....................... .
14. Sodium is a ....................... .
15. Silicon and antimony are ....................... .
16. Group 1A is called ....................... .
17. Group II A is called as ....................... .
18. Group VII A is called as ....................... .
19. The chemical properties down the group ................... .
20. First period contains .................. elements.
21. Moseley arranged elements according to .................. .
22. The non-metals are present in.............. .
23. The number of shells down the group ....................... .
24. The transition character of elements is from……… to .............. .
*25. The formula of chloride of metal is MCl2 , the metal M belongs to ....................... group.
*26. ....................... group contains all gases at room temperature.
*27. The arrangement of elements in a group of three is called ....................... .
*28. The law used by Newlands to arrange elements is called ....................... .
*29. Elements showing properties of both metals and non-metals are called as................
*30. The element eka-Aluminium is called as ....................... .

Q.I (B) Fill in the blanks :
1. Ice changing to water is an example of ....................... change.
2. When copper powder is heated, ....................... is formed.
3. The substances that undergo changes are called as ....................... .
4. Reactants are represented on ................... .
5. Products are represented on ..................... .
6. Conversion of oil to fats requires ....................... as catalyst.
7. When vegetable oil is mixed with nickel as a catalyst, and heat it with hydrogen gas ....................... are obtained on cooling.
8. The simple form of representation of chemical reaction in words is called .............. .
9. If reactants or products are present as solution in excess of water, the symbol used is ....................... .
10. According to ......................., the total mass of reactants is equal to the total mass of products during a chemical reaction.
*11. The chemical formula of POP is ............ .
*12. The chemical reaction during which hydrogen is lost is called as ....................... .
*13. Corrosion can be prevented by using ....................... .
*14. When acids and alkalis react together, ....................... and .......................  is formed.
*15. The chemical reaction in which heat is evolved is called as .......................   reaction.
16. When oil and fats are oxidized or even allowed to stand for a long time,  they become ....................... .

Q.I (C) Fill in the blanks :
1. Acids turn ....................... litmus .............. .
2. Bases turn ....................... litmus................
3. Mixture of several indicators is called as ....................... indicator.
4. ....................... helps in determining the hydrogen ion concentration in the solution.
5. In pH scale, 0 is ....................... .
6. In pH scale, 14 is ....................... .
7. In pH scale, 7 indicates ....................... .
8. pH of pure water is ....................... .
9. Tamarind has a ....................... taste.
10. The human body works within the pH range of ....................... .
11. ....................... gas burns with a pop sound making a little explosion.
12. Reactivity of base with non-metallic oxide is an example of ..........reaction.
13. Phenolphthalein indicator turns ....................... in the basic medium.
14. Presence of chlorides and sulphates of Ca, Mg makes water ....................... .
*15. Most of the acidic substances are ....................... in taste.
*16. Phenolphthalein is ....................... type of indicator.
*17. The strength of basic substance is represented by ....................... .
*18. pH scale ranges between ....................... to ....................... .
*19. Acid and base react to form ....................... and ....................... .
*20. Sodium or potassium salt of higher fatty acids are ....................... .
*21. In FeSO4, 7H2O, 7H2O represents as ....................... .
*22. 10% NaCl is known as ....................... .

Q.I (D) Choose the correct alternatives and rewrite the complete sentences
*1. 1mA = ..................... .
(a) 103 A (b) 10-3A   (c) 106 A (d) 10-3  A
*2. To increase the effective resistance in a circuit the resistors are connected in ..................... .
(a) series (b) parallel  (c) series and parallel (d) non of these
*3. 1 kilowatt hr = ..................... .
(a) 4.6 × 106 joule (b) 3.6 × 106 joule  (c) 30.6 × 106joule (d) 3.6 × 105 joule
*4. The current passing through a 3 Ω resistor if P.D. of 12V is applied across it is ............... .
(a) 36 A (b) 4 A   (c) 0.25 A (d) 15 A
5. The S.I. unit of potential difference is ..................... .
(a) ampere (b) volt  (c) ohm (d) joule
6. The unit of electric charge is ..................... .
(a) ampere (b) coulomb  (c) volt (d) ohm
7. One ..................... is the potential difference when one joule of work is
done to move a charge of one coulomb.
(a) ohm (b) coulomb   (c) volt (d) ampere
8. The S.I. unit of electric current is .............. .
(a) ampere (b) coulomb  (c) volt (d) ohm
9. According to Ohm’s law, longer the length of wire, ..................... is the
resistance for given cross section of wire.
(a) lower (b) greater  (c) zero (d) constant
10. A substance which does not allow charges to pass through it, easily is
called as ..................... .
(a) metal (b) conductor  (c) insulator (d) semiconductor
11. If a current of 0.1 A is passed through a wire of resistance 20 ohm, the potential difference across the wire is ..................... .
(a) 20 ohm (b) 20 volt   (c) 10 volt (d) 2 volt
12. Electric current is measured with the help of a device called ..................... .
(a) an ammeter (b) a volt meter   (c) a thermometer (d) a calorimeter
13. The equivalent resistance of a parallel combination is ..................... than
each of the individual resistance.
(a) greater (b) smaller   (c) stronger (d) more
14. If two resistances of 10 ohm and 15 ohm are connected in parallel the equivalent resistance will be ..................... ohm.
(a) 25    (b) 6    (c) 1/6  (d) 150
15. In conductors, electrons are always in the state of ..................... motion.
(a) lower to higher (b) opposite  (c) similar (d) random
16. A diagram which indicates how different components in a circuit have
been connected by using the electrical symbols for the components is called............ .
(a) ray diagram (b) component diagram  (c) venn diagram (d) circuit diagram
17. The electrons flow from negative terminal to positive terminal of the cell but the ..................... of current is from positive terminal to negative terminal of the cell.
(a) conventional direction (b) electron current  (c) real current (d) negative
18. The SI unit of resistivity is ..................... .
(a) ohm–metre (b) ohm-(metre)2  (c) ohm (d) joule
19. When potential dif ference is applied between two ends of a wire ................ in it.
(a) heat is produced (b) charge is set up (c) charge move randomly (d) electrons move randomly
20. The quantity of heat produced depends upon ..................... .
(a) square of the current (I2)
(b) resistance of the conductor (R)
(c) time for which the current flows (t)
(d) I2Rt
21. 1 cal = ..................... joule.
(a) 107 (b) 105    (c) 41.8 (d) 4.18
22. Heat energy produced is expressed in terms of ..................... .
(a) calorie (b) newton  (c) ampere (c) coulomb
23. Tungsten in bulb has ..................... .
(a) high melting point (b) high charge  (c) high P.D. (d) high insulation
24. Fuse is made up of ..................... .
(a) iron and carbon (b) lead and Tin (c) copper and Zinc (d) copper and Aluminum
25. The ..................... in the fuse is such that it melts when a current passing
through it exceed a certain value.
(a) length (b) diameter  (c) charge (d) distance
26. In surgery finely heated ..................... wire is used for cutting tissues much more efficiently than a knife.
(a) tungsten (b) lead and tin (c) platinum (d) iron
27. The charge of an electron is ................... .
(a) 1.6 × 10–19 C (b) 1.6 × 10–32 C  (c) 1.6 × 10–19 A (d) 1.6 × 10–32 V
28. 1 µ A (micro-ampere) = ..................... .
(a) 10–5 A (b) 10–6 A (c) 10–3 A (d) 10–2 A
29. ..................... is the electric discharge travelling from clouds at high
potential to the earth.
(a) Lightning (b) Tornado  (c) Thunder (d) Sparks
30. The resistivity of ..................... is the highest in conductors.
(a) nickel (b) mercury  (c) chromium (d) manganese
Q.I (E) Choose the correct alternatives and rewrite the complete sentences
*1. The device used for producing current is called a ..................... .
(a) voltmeter (b) ammeter (c) galvanometer (d) generator
*2. At the time of short circuit, the current in the circuit ..................... .
(a) increases (b) decreases (c) remains (d) increases in steps
*3. The direction of the magnetic field around a straight conductor carrying  current is given by ..................... .
(a) right hand rule (b) Fleming’s left hand rule
(c) Fleming’s right hand rule (d) non of these
4. The relation between electricity and magnetism was first established by  ..................... .
(a) Ohm (b) Ampere (c) Oersted (d) Moseley
5. The region around magnet is called as .............. .
(a) magnetic Area (b) magnetic field (c) magnetic loop (d) magnetism
6. Oersted proved that when current passes through a conducting wire it  produces ..................... .
(a) charge (b) current (c) magnetic field (d) potential difference
7. The relative strength of magnetic field is shown by ..................... .
(a) degree of closeness of field lines (b) optical lines
(c) current flowing (d) potential difference
8. The magnetic field produced at centre of circular wire is inversely
proportional to ..................... .
(a) magnitude of current (b) radius of circular wire
(c) resistance of wire (d) time for which current is passed
9. Solenoid has properties similar to ..................... .
(a) magnet (b) resistance (c) electric motor (d) optical instruments
10. The magnetic field in solenoid depends on ..................... .
(a) current and number of turns per unit length
(b) current only
(c) Number of turn per unit length
(d) material
11. In India, the frequency of A.C is ..................... cycles per second.
(a) 50 (b) 100   (c) 60 (d) none
12. The magnetic field produced at centre of circular wire is directly proportional  to ..................... .
(a) magnitude of current passing through it
(b) radius of the loop
(c) resistance of wire
(d) time for which the current passes through it.
13. The non-oscillating current is called as ..................... .
(a) A.C. (b) D.C. (c) electric current (d) non-oscillating current
14. The ..................... at any point on the magnetic lines of force gives the  direction of the magnetic field at that point.
(a) tangent (b) circle (c) radius (d) chord
15. ..................... is an alloy of iron, nickel, aluminium and titanium.
(a) Nipermag (b) Nichrome   (c) Alnico (d) Tin
16. ..................... is aluminium-nickel-cobalt alloy.
(a) Alnico (b) Tin    (c) Nichrome (d) Nipermag
17. If a conductor is moving inside a magnetic field or magnetic field is changing  around a fixed conductor ..................... is generated.
(a) electric current (b) heat    (c) sparks (d) light
18. The process, by which a changing magnetic field in a conductor induces a  current in another conductor, is called ..................... .
(a) electromagnetic induction (b) potential difference  (c) electrostatics (d) sparks
19. If a live wire and a neutral wire comes in direct contact or touch each  other, ..................... takes place.
(a) short circuiting (b) magnetic effect  (c) heating (d) electro-magnetism
20. ..................... means the flow of large amount of current in the circuit  beyond the permissible value of current.
(a) Overloading (b) Drip  (c) Sparkling (d) Resistance
21. French scientist ..................... suggested that the magnet must also exert  an equal and opposite force on the current carrying conductor.
(a) joule (b) newton  (c) ampere (d) fleming
22. ..................... reverses the direction of current in the armature coil of  electric motor.
(a) Brushes (b) Armature coil   (c) Magnet (d) Commutator
23. The direction of induced current in an AC generator changes once in each  ..................... .
(a) two revolutions (b) one revolution   (c) half revolution (d) one fourth revolution
24. A ..................... is used to detect the presence of current in a circuit.
(a) voltmeter (b) variable resistance    (c) galvanometer (d) Tap key
25. Electro-magnetic induction was first studied by ..................... .
(a) Ampere (b) Faraday   (c) Oersted (d) Joule
Q.I (F) Choose the correct alternatives and rewrite the complete sentences                             MIRROR
1. The image formed by a concave mirror is ..................... .
(a) always virtual and erect
(b) always virtual and inverted
(c) virtual if the object is placed between the pole and the focus
(d) virtual if the object is beyond the focus
2. A concave mirror forms a virtual image of an object placed ..................... .
(a) at infinity
(b) at the centre of curvature of the mirror
(c) at the focus of the mirror
(d) between the focus and the mirror
3. A convex mirror always forms an image which is ..................... than the object size.
(a) larger (b) smaller  (c) double (d) three times
4. No matter how far you stand from a spherical mirror, your image appears erect. The mirror may be ..................... .
(a) Plane (b) concave  (c) convex (d) either plane or convex
5. In case of a concave mirror, an erect image is ..................... .
(a) real and enlarged (b) real and diminished
(c) virtual and diminished (d) virtual and enlarged
6. ..................... images can be displayed on a screen.
(a) Virtual (b) Real  (c) Virtual and erect (d) Virtual and inverted
7. A rear view mirror of a car is ..................... .
(a) Plane mirror (b) Concave mirror
(c) Convex mirror (d) Cylindrical mirror
8. An image of an object placed at infinite distance from a concave mirror is formed at ..................... .
(a) the focus of the mirror (b) behind the mirror  (c) centre of curvature (d) infinity
9. The distance of focus F from the pole P is termed as the ..................... of the mirror.
(a) radius of curvature (b) centre of curvature  (c) principal axis (d) focal length
10. A concave mirror is also called as a ..................... mirror.
(a) converging (b) diverging  (c) plane (d) outward curved
*11. A ray of light parallel to principal axis after reflection from concave mirror passes through ..................... .
(a) centre of curvature (b) focus  (c) pole (d) optical centre
12. The centre of the spherical mirror is called ..................... .
(a) pole (b) centre of curvature  (c) principal axis (d) focus
13. The image made by a plane mirror is a ..................... image.
(a) real (b) virtual  (c) inverted (d) diminished
14. According to the new sign convention, the ..................... of the mirror is taken as origin.
(a) focus (b) pole   (c) optical centre (d) centre of curvature
15. Turning back of light from the surface on which it falls is called ..................... .
(a) refraction (b) reflection of light (c) dispersion (d) rectilinear propagation
16. The size of the image of an object placed at the focus of a concave mirror is
..................... .
(a) erect (b) highly enlarged (c) same size (d) diminished
17. A convex mirror is also called as a ..................... mirror.
(a) converging (b) plane (c) diverging (d) inward curved
18. To obtain a real, inverted and enlarged image using a concave mirror, the
object should be placed ..................... .
(a) between the focus and centre of curvature of the mirror
(b) at infinity
(c) beyond centre of curvature
(d) at centre of curvature
19. If magnification is negative, the image is ..................... with respect to the
object.
(a) inverted (b) enlarged (c) erect (d) diminished
LENS
20. The image formed by a concave lens ..................... .
(a) is always virtual and erect
(b) is always real and inverted
(c) is virtual if the object is placed between the optical centre and the focus
(d) Is virtual if the object is beyond the focus
*21. The focal length of ..................... lens is positive.
(a) concave (b) bifocal (c) convex (d) double concave
*22. The image of an object is formed behind ..................... in hypermetropia.
(a) cornea (b) retina (c) lens (d) iris
*23. An optical device used by watch repairers is ..................... .
(a) compound microscope (b) telescope (c) simple microscope (d) spectrometer
*24. The power of spectacle for myopic eye is ..................... .
(a) positive (b) negative (c) zero (d) positive and negative
25. The human eye can focus objects at different distances adjusting the focal length of the eye due to ..................... .
(a) presbyopia (b) power of accomodation (c) hypermetropia (d) myopia
26. The tendency of pupil to adjust the opening for light is called ..................... .
(a) adaptation (b) power of accomodation  (c) light control (d) perception
27. A lens does not produce any deviation of a ray of light passing through its ..................... .
(a) centre of curvature (b) optical centre  (c) second focal point (d) axial point at a distance of 2F
28. The power of a convex lens of focal length 25 cm is ..................... .
(a) 4 dioptre (b) -4 dioptre  (c) 1/25 dioptre (d) -1/25 dioptre
29. A person suffering from myopia ..................... .
(a) cannot see nearby objects clearly
(b) cannot see distant object clearly
(c) can see nearby as well as distant objects clearly
(d) can neither see nearby objects nor distant objects clearly
30. A well lit object produces ..................... incident rays.
(a) two (b) three  (c) finite (d) infinite
31. The change in focal length of the eye to view objects at different distances is brought about by the ..................... .
(a) retina (b) ciliary muscles  (c) pupil (d) iris
32. The least distance of distinct vision is about ..................... .
(a) 30 cm (b) 35 cm  (c) 20 cm (d) 25 cm 

Q.I (G) Choose the correct alternatives and rewrite the complete sentences
*1. The phenomenon of splitting of light into its component colours is
..................... .
(a) reflection (b) refraction  (c) dispersion (d) rectilinear propagation
*2. Very fine particles mainly scatter ..................... light.
(a) red (b) green  (c) blue (d) yellow
*3. The phenomenon of change in the ..................... of light when it passes from one transparent medium to another is refraction.
(a) Wavelength (b) frequency  (c) direction (d) amplitude
*4. The refractive index depends upon the ..................... of propagation of  light in different media.
(a) relative speed (b) density of medium  (c) amplitude (d) frequency
5. The ratio sin i / sin r = constant is called as ..................... .
(a) dispersion (b) spectrum (c) refractive index (d) proportionality constant
6. The apparent random wavering of hot air above the heated roads causes a  phenomenon called as ..................... .
(a) looming (b) mirage (c) spectrum (d) dispersion
7. The refractive index of water is ..................... .
(a) 1.33 (b) 1.31 (c) 1.36 (d) 1
8. The refractive index of ..................... is the highest.
(a) alcohol (b) flint glass (c) diamond (d) canada balsam
9. When a ray of light travels from an optically denser medium to an optically  rarer medium, the ray bends ..................... .
(a) towards the normal (b) away from the normal
(c) straight (d) backwards
10. After dispersion ..................... colour deviates the most.
(a) red (b) green  (c) yellow (d) violet
11. When white light is dispersed into seven colours ..................... colour  bends least.
(a) blue (b) violet  (c) red (d) yellow
12. ..................... light is scattered the least by the atmosphere.
(a) Red (b) Violet  (c) Yellow (d) Green
13. ..................... was the first scientist to use a glass prism to obtain the  spectrum of sunlight.
(a) Oersted (b) Joule  (c) Newton (d) Faraday
14. The apparent depth of an object placed in a denser medium and seen  through a rarer medium is ..................... .
(a) half its real depth (b) equal to the red depth
(c) less than real depth (d) greater than real depth
15. A prism is a transparent medium bound by ..................... plane surfaces  inclined at an angle.
(a) two (b) three  (c) four (d) one
16. When a ray of light passes from rarer medium to a denser medium, the  angle of refraction is ..................... .
(a) equal to angle of incidence
(b) independent of angle of incidence
(c) smaller than angle of incidence
(d) greater than angle of incidence
17. The apparent position of a star in the sky is ..................... .
(a) slightly lower than its actual position
(b) slightly higher than its actual position
(c) same as that of its actual position
(d) far away from its actual position
18. Advanced sunlight and delayed sunset increases duration of day by
..................... minutes.
(a) 30 (b) 4  (c) 1 (d) 10
19. Amongst the following ..................... has the highest refractive index.
(a) air (b) ice  (c) water (d) alcohol
20. When a ray is incident normal to the interface between any two transparent  medium, the angle of incidence is ..................... .
(a) greater than angle of refraction (b)zero  (c) less than angle of refraction (d) 45º
21. The stars are ..................... sources of light as they are very far away.
(a) point (b) infinite  (c) important (d) primary
22. Twinkling of stars is due to change in ..................... of atmosphere
(a) temperature (b) refractive index  (c) pressure (d) climate
23. ..................... won a nobel prize for his outstanding work on scattering of  light.
(a) Newton (b) Joule (c) Dr. C. V. Raman (d) Ohm
Q.I (H) Fill in the blanks :
1. ....................... element that has the highest melting point.
2. ....................... is the only non-metal in liquid state.
3. Chocolates are wrapped in an aluminium foil, this is an application of
property of ....................... .
4. PVC stands for....................... .
5. Metal oxides are usually ....................... in nature.
6. Aluminium oxide is ....................... in nature.
7. Metals react with water to form a metal hydroxide and ....................... gas
is liberated.
8. Metals react with dilute acids to give ....................... and .......................
gas is liberated.
9. Sodium is a ....................... coloured metal.
10. Chlorine is a ....................... .
11. The most unreactive metals i.e. which are not affected by air and water
e.g. silver, gold and platinum are generally found in ....................... state.
12. The symbol of Aluminium is ....................... .
13. The valency of aluminium is ....................... .
14. Aluminum undergoes an oxidation reaction forming a thin layer of
....................... .
15. Potassium is the ....................... metal.
16. Pure gold is ....................... gold.
17. Pure gold is alloyed with ....................... or ....................... to make ornaments.
18. Aqua regia can dissolve metals like....................... and ....................... .
Q.I (I) Fill in the blanks :
1. The number of valence electrons in carbon are ....................... .
2. The property of direct bonding between atoms of the same element to form
chain is known as ....................... .
3. In saturated hydrocarbons two carbon atoms are linked by ....................... .
4. ....................... is an alkyne.
5. Ethene has ....................... .
6. The molecular mass of two adjacent members in homologous series of
alkane differs by ....................... .
7. ....................... is the first member of alkane family.
8. There are ....................... carbon atoms in butane.
9. ....................... gas is called marsh gas.
10. ....................... is first homolog of alkene series.
11. Vinegar is ....................... .
12. Molecular formula of benzene is ....................... .
13. In the earlier days, the compounds obtained from animal or plant kingdom
were called as ....................... .
14. Atomic number of carbon is ....................... .
15. An organic compound containing only carbon and hydrogen elements is
called ....................... .
*16. General molecular formula of alkane is ....................... .
17. Molecular formula of ethane is ....................... .
18. The general molecular formula of alkene is ....................... .
19. Hydrocarbons in which two carbon atoms are linked by triple bond is called
....................... .
20. The general formula for alkyne is ....................... .
21. Organic compounds with same general molecular formula are known as
....................... .
*22. The organic compounds having double or triple bond in them are termed as
....................... .
*23. ....................... are known as parent organic compound.
*24. Covalent compounds are generally soluble in ....................... solvents.
*25. Triple bond can be obtained by sharing ....................... pairs or .......................electrons.
*26. Hydrocarbons necessarily contain ....................... and ....................... .
27. Methane is also called ....................... .
28. The electronic configuration of carbon is ....................... .
29. Carbon has ....................... electrons in its outermost orbit, hence it is
....................... .
30. Bond formed by sharing of electrons are known as ....................... .
31. All hydrocarbons burn in air to form ....................... and ....................... .
32. Ethanol is called ....................... or ....................... .
33. Ethanol has a formula ....................... .
34. When sodium comes in contact with ethyl alcohol it gives .......................
gas.
35. Ethanoic acid is commonly known as ....................... acid.
36. Acetic acid has the formula ....................... .
37. Below 290k acetic acid solidifies to an ice like mass called .......................     
Q.I (J) Choose the correct alternatives and rewrite the complete sentences
1. The organisms which synthesize their own organic food are called as
....................... .
(a) autotrophs (b) heterotrophs (c) parasites (d) saprophytes
2. Organisms that depend on other organisms for their food are .......................
organisms.
(a) autotrophic (b) heterotrophic (c) parasitic (d) saprophytic
3. The alimentary canal begins with the ....................... .
(a) stomach (b) oesophagus (c) mouth (d) small intestine
4. Enzyme ....................... breaks down starch into a simple sugar maltose.
(a) pepsin (b) salivary amylase  (c) pancreatic amylase (d) trypsin
5. The enzyme ....................... digests proteins in the stomach.
(a) trypsin (b) pepsin  (c) salivary amylase (d) pancreatic amylase
6. The ....................... is the longest part of the alimentary canal.
(a) stomach (b) oesophagus  (c) small intestine (d) large intestine
7. Unused glucose is stored in the liver in the form of ....................... .
(a) starch (b) glycogen  (c) proteins (d) fats
8. Cellular or internal respiration takes place in the ....................... of the
cells to release energy in the form of ATP.
(a) mitochondria (b) cytoplasm (c) nucleus (d) vacuoles
9. In aquatic animals ....................... are the site for uptake of dissolved
oxygen into the blood by diffusion.
(a) lungs (b) skin (c) gills (d) trachea
10. The human respiratory tract starts with the ....................... .
(a) mouth (b) larynx  (c) lungs (d) nostrils
11. The process of transportation of materials in animals is cal led
....................... .
(a) assimilation (b) translocation  (c) circulation (d) absorption
12. Human heart weighs about ....................... .
(a) 500 gm (b) 360 gm  (c) 1000 gm (d) 250 gm
13. In plants, the gaseous excretory materials are eliminated by ....................... .
(a) transpiration (b) diffusion  (c) osmosis (d) translocation
Q.I (K) Fill in the blanks :
*1. ....................... artery takes the blood to the lungs for oxygenation.
*2. ....................... is the largest gland in the body.
*3. The digested food is absorbed by the ....................... in the small intestine.
*4. Lymph flows in ....................... direction.
5. The processes that are common to all living organisms are called as the
....................... .
6. Food contains several components called as ....................... .
7. The crushed food is wetted with saliva secreted by the ....................... .
8. Food is converted into simpler molecules with the help of biological catalysts
called as ....................... .
9. The food is pushed forward in the canal due to rhythmic contraction and
relaxation of the muscles of the canal called as ....................... .
10. ....................... protects the inner lining of the stomach from the action of
acids under normal conditions.
11. The exit of the food from the stomach is regulated by the ....................... .
12. Carbondioxide enters into the leaves through tiny pores present on the
surface of the leaf called ...................... .
13. The heart is covered by the ...................... .
14. The basic filtration unit in the kidney is a cluster of thin walled blood
capillaries called as a ....................... .
15. Each nephron has a cup shaped thin walled upper end called ...................... .
16. Bowman’s capsule contains a bundle of blood capil laries cal led
....................... .
17. In some plants, waste is in the form of calcium oxalate crystals called as
....................... .
18. ....................... is the fluid connective tissue in human beings.
Q.I (L) Choose the correct alternatives and rewrite the complete sentences
1. .................... is necessary to obtain energy from glucose and fatty acid.
(a) Oxygen (b) Hydrogen  (c) Water (d) Nitrogen
2. In certain sensitive plants like Mimosa, movement is in response to the
stimulus of ..................... .
(a) gravity (b) air  (c) light (d) touch
3. The movement of the plant in response to the stimulus of light is called
..................... movement.
(a) gravitropic (b) hydrotropic  (c) phototropic (d) chemotropic
4. When light falls on a part of growing plant, a hormone called .....................
is synthesized at the tip of the shoot.
(a) auxin (b) abscissic acid  (c) gibberellins (d) cytokinins
5. The movement of the root system towards the stimulus of gravity is called
..................... movement.
(a) gravitropic (b) hydrotropic  (c) phototropic (d) chemotropic
6. The movement of the root system towards the stimulus of water is called
..................... movement.
(a) gravitropic (b) hydrotropic  (c) phototropic (d) chemotropic
7. ..................... hormones help in the growth of the stem.
(a) Auxins (b) Abscissic acid  (c) Gibberellins (d) Cytokinins 
8. ..................... hormones promote cell division.
(a) Auxins (b) Abscissic acid  (c) Gibberellins (d) Cytokinins
9. ..................... is a plant hormone which inhibits growth wilting of leaves.
(a) Auxin (b) Abscissic acid  (c) Gibberellins (d) Cytokinins
10. The ..................... is the main thinking part of the brain.
(a) cerebrum (b) cerebellum  (c) medulla oblongata (d) spinal cord
11. The brain can stay alive for ..................... without oxygen.
(a) 4-6 hours (b) 5-6 hours  (c) 24 hours (d) 4-6 minutes
Q.I (M) Fill in the blanks :
*1. ..................... do not possess a nervous system.
*2. Response to the stimulus of touch is called ..................... whereas response to the stimulus of chemicals is called as.................. .
*3. Brain is the main ..................... centre of the body.
*4. The loss of water from the plants is known as ..................... .
5. ..................... refers to the systematic regulation of various activities.
6. ..................... means the orderly execution of the activities.
7. Transpiration takes place in the leaves through the ..................... .
8. The food is mixed with the ..................... in the saliva secreted by the
salivary glands.
9. The movement or growth of any part of a plant in response to an external
stimulus is called ..................... .
10. The plants use ..................... means to transfer information from one cell
to another.
11. The nerves are composed of neurons and ..................... .
12. The neurons are specialized cells capable of transmitting ..................... .
13. ..................... neurons conduct impulses from the sense organs to the
brain and spinal cord.
14. ..................... neurons conduct impulses from the brain and spinal cord to
the effector organs.
15. ..................... neurons perform the integrative functions of the nervous
system.
16. ..................... keeps the CNS well nourished and also protects it by absorbing mechanical shocks.
17. The chemical control is brought about by chemical substances called
..................... .
18. The hormones are secreted by the ..................... glands.
19. Endocrine glands are also known as the ..................... glands.
20. Hormones are also referred to as ..................... .
21. Insect ..................... is under hormonal control.
22. In frogs ..................... secretion stimulates the metamorphosis from tadpole
to adult frog.
23. In the ....................., hormones induce colour changes and are influential
in regulating development.
24. The left hemisphere of the brain has ..................... more neurons than the right hemisphere.
25. ..................... of blood flows through the brain every minute.
26. In certain coelenterates like ....................., the nervous system is at a
very primitive stage of developments.
Q.I (N) Choose the correct alternatives and rewrite the complete sentences
1. The filament of spirogyra undergoes ....................... resulting in numerous
filaments.
(a) budding (b) regeneration (c) fragmentation (d) spore formation
2. ....................... reproduces from the buds on the leaf margin.
(a) Lotus (b) Rose  (c) Jasmine (d) Bryophyllum
3. ....................... is the receptive organ on which pollen germinates.
(a) Style (b) Stigma  (c) Anther (d) Ovary
4. The elongated part of carpel bearing stigma at its tip is called ..................... .
(a) style (b) stigma  (c) anther (d) ovary
5. In plants, male germ cells are produced by ....................... .
(a) filament (b) anther  (c) pollen grains (d) stamen
6. ....................... serves as nutritive tissue for the growing embryo.
(a) Embryo sac (b) Endosperm  (c) Ovary (d) Fruit
7. The ovule develops into a ....................... .
(a) fruit (b) seed  (c) flower (d) ovary
8. The ovary develops into a ....................... .
(a) fruit (b) seed  (c) flower (d) ovule
9. Testes secrete the hormone ....................... which brings about changes
in boys during puberty.
(a) progesterone (b) estrogen  (c) thyroxine (d) testosterone
10. Immature sperms travel to the ....................... for development and storage.
(a) vas deferens (b) penis (c) testes (d) epididymis
11. ....................... is a passage through which the sperm travels towards the
urethra.
(a) Vas deferens (b) Penis  (c) Epididymis (d) Seminal vesicle
12. The ovaries secrete the hormone ....................... which brings about changes
in girls during puberty.
(a) progesterone (b) estrogen  (c) thyroxine (d) testosterone
13. Planaria reproduces by ....................... .
(a) fragmentation (b) budding  (c) binary fission (d) regeneration
Q.I (O) Fill in the blanks :
*1. The two main methods of reproduction are .. .. .. .. .. .. .. .. .. .. .. . and
....................... .
*2. The functional unit in a plant’s sexual reproduction is ....................... .
*3. The male reproductive part of a flower is ....................... .
*4. When the transfer of pollen from an anther to the stigma occurs in the
same flower, the process is called ....................... .
*5. ....................... give rise to variety and diversity.
*6. Hydra uses regenerative cel ls for reproduction in the process of...................... .
*7. Yeast reproduces by ....................... .
*8. During unfavourable conditions, the amoeba secretes a hard covering called
....................... .
*9. A basic process in reproduction is the creation of a ....................... copy.
*10. ....................... is necessary to maintain the number of individuals of a
species.
11. In asexual reproduction the cells divide ....................... .
12. The ....................... of bread mould (Mucor) are thread like structures.
13. The mould forms spores inside a ....................... .
14. ....................... is the process by which an entire organism is reproduced
in a genetically identical manner, from a parent organism.
15. ....................... enables organisms to adapt and survive in the changing
environment.
16. Stamen is made up of ....................... and ....................... .
17. If pollen is transferred from one flower to the flower of another plant of the
same species, it is known as ....................... .
18. One male gamete fuses with the egg cell to form ....................... .
19. The second male gamete fuses with the secondary nucleus in the embryo
sac to form ....................... .
20. ....................... is a muscular tube that extends from the vaginal opening
to the uterus.
21. ....................... provides the route for the menstrual blood to leave the
body during menstruation.
22. ....................... connect uterus to the ovary.
23. The embryo gets all the nutrients and oxygen from its mother’s blood in
the oviduct supplied through the ....................... .
24. The ....................... has prepared guidelines and considered reproductive
health as a fundamental human right.
25. ....................... was the first mammal to be cloned from an adult cell rather
than an embryo.
26. As soon as the egg cell (zygote) is fertilized, it begins to divide until it
becomes a ball of cells called ....................... .

Q.I (P) Choose the correct alternatives and rewrite the complete sentences :
1. Resemblance and differences is the result of ..................... .
(a) heredity (b) fertilization  (c) evolution (d) selection
2. The quantity of hormones produced by the plants depends upon the
efficiency of the concerned ..................... .
(a) chromosome (b) enzyme  (c) gene (d) DNA
3. In human beings there are ..................... chromosomes.
(a) 46 (b) 23  (c) 52 (d) 24
4. The theory of natural selection was proposed by ..................... .
(a) Mendel (b) Lamarck  (c) Charles Darwin (d) Robert Hooke
5. A systematic study of fossils and its occurence revealed that the deepest
layers were found to have fossils of ..................... .
(a) vertebrates (b) invertebrates  (c) ambhibians (d) plants
6. ..................... is a connecting link between annelida and arthropoda.
(a) Peripatus (b) Cockroach  (c) Crab (d) Earthworm
7. Inheritance of acquired characteristics is also called .....................
inheritance.
(a) hard (b) soft  (c) acquired (d) crisscross
Q.I (Q) Fill in the blanks :
*1. In ..................... mode of reproduction, the offsprings are with minor differences.
*2. Both the parents contribute equal amount of ..................... material to
the offspring.
*3. Dominant character masks the ..................... character.
*4. Selection by nature is not ..................... but ..................... .
5. Mendel’s experiments were based on a number of visible contrasting
characters of garden peas ..................... .
6. A fragment of DNA that provides complete information about one protein is
known as the ..................... for that protein.
7. All children inherit ..................... chromosome from their mother.
8. Sex determination in human beings is ..................... .
9. ..................... are collected from different levels of depths.
10. Minor differences occur in asexual reproduction due to inaccuracies
occuring in ..................... .
A.    Answers.
1.    Periods
2.    Decreases
3.    7
4.    2
5.    2
6.    0
7.    Donate
8.    Varies gradually
9.    Remains the same
10.  Metals
11.  Gains or shares
12.  Helium
13.  2,8
14.  Metal
15.  Metalloids
16.  Alkali metals
17.  Alkaline earth metals
18.  Halogens
19.  Remain the same
20.  2
21.  Atomic number
22.  Upper right hand corner
23.  Increases
24.  Metallic to non – metallic
25.  IIA
26.  18 or zero
27.  Triad
28.  Newlands Law of octaves
29.  Metalloids
30.  Gallium
B.    Answers
1.    Physical
2.    Copper oxide
3.    Reactants
4.    Left hand side
5.    Right hand side
6.    Nickel
7.    Fats
8.    Word equation
9.    Aq
10.  Law of conservation of mass
11.  (CaSO4).H2O
12.  Oxidation reaction
13.  Anti rust solution, coating surface by p;aint, process like galvanizing and electro – plating
14.  Salt and water
15.  Exothermic reaction
16.  Racid.
C.    Answers.
1.    Blue, red
2.    Red, blue
3.    Universal
4.    pH scale
5.    most acidic
6.    most basic
7.    neutral
8.    7
9.    Sour
10.  7.35 to  7.45
11.  Hydrogen
12.  Neutralization
13.  Pink
14.  Hard
15.  Sour
16.  Synthetic
17.  pOH
18.  0.14
19.  Salt, water
20.  Soap
21.  Water of crystalization
22.  Brine
D.    Answers.
1.    10-3 A
2.    Series
3.    3.6 x 106 joule
4.    4A
5.    Volt
6.    Coulomb
7.    Volt
8.    Ampere
9.    Greater
10.  Insulator
11.  2 volt
12.  An ammeter
13.  Smaller
14.  6
15.  Random
16.  Circuit diagram
17.  Conventional direction
18.  Ohm – metre
19.  Heat is produced
20.  I2Rt
21.  4.18
22.  Calorie
23.  High melting point
24.  Lead and tin
25.  Diameter
26.  Platinum
27.  1.6 x 10-19C
28.  10-6A
29.  Lightning
30.  Mercury
E.    Answers.
1.    Generator
2.    Increases
3.    Right hand rule
4.    Oersted
5.    Magnetic field
6.    Magnetic field
7.    Degree of closeness of field lines
8.    Radius of circular wire
9.    Magnet
10.  Current and number of turns per unit length
11.  50
12.  Magnitude of current passing
13.  D.C.
14.  Tangent
15.  Nipermag
16.  Alnico
17.  Electric current
18.  Electromagnetic induction
19.  Short circuiting
20.  Overloading
21.  Ampere
22.  Commutator
23.  Half revolution
24.  Galvanometer
25.  Faraday
F.    Answers.
1.    Virtual if the object is placed between the pole and the focus
2.    Between the focus and the mirror
3.    Smaller
4.    Convex
5.    Virtual and enlarged
6.    Real
7.    Convex mirror
8.    The focus of the mirror
9.    Focal length
10.  Converging
11.  Focus
12.  Pole
13.  Virtual
14.  Pole
15.  Reflection of light
16.  Highly enlarged
17.  Diverging
18.  Between the focus and center of curvature of the mirror
19.  Inverted
20.  Is always virtual and erect
21.  Convex
22.  Retina
23.  Simple microscope
24.  Negative
25.  Power of acomodation
26.  Adaptation
27.  Optical centre
28.  4 dioptre
29.  Cannot see the distant object clearly
30.  Infinite
31.  Ciliary muscle
32.  25 cm
G.    Answers.
1.     Dispersion
2.    Blue
3.    Direction
4.    Relative speed
5.    Refractive index
6.    Mirage
7.    1.36
8.    Diamond
9.    Away from the normal
10.  Violet
11.  Red
12.  Red
13.  Newton
14.  Less than real depth
15.  Two
16.  Smaller than angle of incidence
17.  Slightly higher than its actual position
18.  4
19.  Alcohol
20.  Greater than angle of refraction
21.  Point
22.  Refraction index
23.  Dr. C.V. Raman.
H.    Answers
1.    Tungsten
2.    Bromine
3.    Malleability
4.    Poly vinyl chloride
5.    Basic
6.    Amphoteric
7.    Hydrogen
8.    Salt and hydrogen gas
9.    Silver
10.  Non – metal
11.  Free or native
12.  Al
13.  3
14.  Aluminium oxide
15.  Most reactive
16.  24 karat
17.  Silver or copper
18.  Gold and platinum
I.     Answers.
1.    4
2.    Catenation
3.    Single bond
4.    Ethyne
5.    Double bond
6.    14
7.    Methane
8.    4
9.    Methane
10.  Ethene
11.  Acetic acid
12.  C6H6
13.  Organic compound.
14.  6
15.  hydrocarbon
16.  CnH2n+2
17.  C2H4
18.  CnH2n
19.  Alkyne
20.  CnH2n-2
21.  Homolog
22.  Unsaturated hydrocarbon
23.  Hydrocarbon
24.  Organic
25.  3,6
26.  Hydrogen, carbon
27.  Marsh gas
28.  2,4
29.  4, tetravalent
30.  Covalent bond
31.  CO2, H2O
32.  Ethyl alcohol, spirit
33.  C2H5OH
34.  Hydrogen
35.  Acetic acid
36.  C2H4O2
37.  Galcial acietic acid.
J.    Answers
1.    Autotrophs
2.    Heterotrophic
3.    Mouth
4.    Salivary amylase
5.    Pepsin
6.    Small intestine
7.    Glycogen
8.    Mitochondria
9.    Gills
10.  Nostrils
11.  Circulation
12.  360 gm
13.  Diffusion
K.    Answers
1.    Pulmonary
2.    Liver
3.    Villi
4.    One
5.    Life process
6.    Nutrients
7.    Salivary glands
8.    Enzymes
9.    Peristaltic movement
10.  Mucus
11.  Sphincter muscle
12.  Stomata
13.  Pericardial membrane
14.  Nephron
15.  Bowman's capsule
16.  Glomerulus
17.  Raphides
18.  Blood
L.    Answers
1.    Oxygen
2.    Touch
3.    Phototropic
4.    Auxin
5.    Gravitropic
6.    Hydrotropic
7.    Gibberllins
8.    Cytokinins
9.    Abscissic acid
10.  Forebrain or cerebrum
11.  4 – 6 minutes
M.  Answers.
1.    Plants
2.    Seismonastic movement,, chemotropism
3.    Thinking
4.    Transpiration
5.    Control
6.    Co – ordination
7.    stomatal opening
8.    enzymes
9.    tropism or tropic movement
10.  electrochemical
11.  neuroglia
12.  electrochemical impulses
13.  sensory
14.  motor
15.  association
16.  cerebrospinal fluid (CSF)
17.  hormones
18.  endocrine
19.  ductless
20.  chemical messengers
21.  metamorphosis
22.  thyroid
23.  arthropods
24.  186 millions
25.  750 – 1000 ml.
26.  Hydra
N.    Answers.
1.    Fragmentation
2.    bryophyllum
3.    stigma
4.    style
5.    pollen grains
6.    endosperm
7.    seed
8.    fruit
9.    testosterone
10.  epididymis
11.  vas deferens
12.  estrogen
13.  regeneration
O.    Answers.
1.    Asexual reproduction, sexual reproduction
2.    Flower
3.    Stamen
4.    Self pollination
5.    Variations
6.    Budding
7.    Budding
8.    Multiple
9.    DNA
10.  Reproduction
11.  Mitotically
12.  Hyphae
13.  Sporangium
14.  Animal cloning
15.  Variation
16.  Anther, filament
17.  Cross pollination
18.  Zygote
19.  Endosperm
20.  Vagina
21.  Vagina
22.  Oviducts
23.  Umbilical cord
24.  WHO
25.  Dolly sheep
26.  Blastocyst
P.    Answers.
1.    Heredity
2.    Enzyme
3.    46
4.    Charles Darwin
5.    Invertebrates
6.    Peripatus
7.    Soft
Q.    Answers
1.    Asexual
2.    Genetic
3.    Recessive
4.    Deliberate, natural
5.    Pisum sativum
6.    Gene
7.    X
8.    Genetical
9.    Fossils
10.  DNA copying




State whether the following statements are true or false. If false
write the corrected statement :
1. Atomic number is the number of protons or electrons in the nucleus.
Ans. True.
2. Fourth and fifth periods are longest periods.
Ans. False. Fourth and fifth periods are long periods, 6th period is the longest
period
3. Newlands arranged elements based on their atomic number.
Ans. False. Newlands arranged elements based on their atomic mass.
4. Mendeleev was the first scientist to create a periodic table for the elements.
Ans. True.
5. Mendeleev arranged 63 elements in the periodic table.
Ans. True.
6. Eka boron is known as Germanium.
Ans. False. Eka boron is known as Scandium
State whether the following statements are true or false. If false
write the corrected statement :
1. Chemical change is a temporary change
Ans. False. It is a permanent change.
2. Camphor sublimes on heating.
Ans. True.
3. (g) indicates the physical state as solid.
Ans. False. (g) indicates the physical state as gas.
4. Conversion of quick lime to slaked lime is an example of displacement
reaction.
Ans. False. It is an example of combination reaction.
5. When left over edible oil is heated, its smell turns foul and develops
rancidity.
Ans. True.
State whether the following statements are true or false. If false
write the corrected statement :
1. When the pH value is between 0 to 7, the solution is acidic.
Ans. True.
2. A substance having pH value 7 will have effect on litmus paper.
Ans. False. A substance having pH value 7 will have no effect on litmus paper.
3. Bases are sweet to taste.
Ans. False. Bases are bitter to taste.
4. Carbon dioxide is a non-metallic oxide.
Ans. True.
5. Hydrogen ions cannot exist alone, it always combines with water and form
hydronium ion.
Ans. True.
6. Sodium chloride is a neutral salt.
Ans. True.
7. The dehydration of copper sulphate is a reversible process.
Ans. True.

State whether the following statements are true or false. If false
write the corrected statement :
*1. Magnetic poles exists in pairs.
Ans. True.
*2. Magnetic field increase as we go away from a magnet.
Ans. False. Magnetic field decreases as we go away from a magnet.
*3. Magnetic lines of force always cross each other.
Ans. False. Magnetic lines of force never cross each other.
*4. Electric generator is used to generate current.
Ans. True.
5. The magnetic field of solenoid has few properties similar to bar magnet.
Ans. False. The magnetic field of solenoid has all properties similar to bar magnet.
6. The direct current always flows in one direction.
Ans. True.
7. Direct current is used for long distance transportation of electricity.
Ans. False. A.C. is used for long distance transportation of electricity.
8. Water should be used in electrical fire.
Ans. False. Water should not be used in electrical fire.
9. If there is fire caused by sparking, the main switch should be switched off
immediately.
Ans. True.
10. Magnetic lines of force start from south pole and ends on south pole.
Ans. False. Magnetic lines of force start from north pole and ends on south pole.
State whether the following statements are true or false. If false
write the corrected statement :
1. Silver is the best conductor of electricity and next in order is copper.
Ans. True.
2. PVC is a bad conductor of electricity.
Ans. True.
3. Aluminium is a non-metal.
Ans. False. Aluminium is a metal.
4. Almost all metals react with oxygen to form metal oxide, but the reactivity
differs for different metals.
Ans. True.
5. Most metal oxides are insoluble in water.
Ans. True.
6. Metal oxides dissolve in water to form alkalis.
Ans. True.
7. In anodizing technique, a thin film of aluminium oxide is formed on surface
of cathode.
Ans. False. In anodizing technique, a thin film of aluminium oxide is formed on
surface of anode.
8. Silver and gold react with dilute acids.
Ans. False. Silver and gold do not react with dilute acids.
9. Chlorine is a greenish coloured poisonous gas that was used as a weapon
during World War I.
Ans. True.
10. Most metals however are found in combined state in the form of their
oxide ores, carbonate ores, or sulphide ores.
Ans. True.
State whether the following statements are true or false. If false
write the corrected statement :
1. Study of organic compounds is called organic chemistry.
Ans. True.
2. Hydrocarbons are the compounds containing carbon and hydrogen elements
only.
Ans. True.
3. Hydrocarbons with double bond are called saturated hydrocarbons.
Ans. False. Hydrocarbons with single bond are called saturated hydrocarbons.
4. Ethylene contains carbon carbon triple bond.
Ans. False. Ethylene contains carbon-carbon double bond.
State whether the following statements are true or false. If false
write the corrected statement :
1. Lack of genetic variation is the advantage of asexual reproduction.
Ans. False. Lack of genetic variation is the disadvantage of asexual reproduction.
2. DNA copies are identical to the original.
Ans. False. DNA copies are similar but not identical to the original.
3. Mitosis is a process in which halving the number of chromosomes takes
place.
Ans. False. Mitosis is a process in which the chromosome number is restored.
4. Meiosis is a process in which halving the number of chromosomes takes
place.
Ans. True.
5. Testes secrete the hormone testosterone.
Ans. True.
6. Immature sperms travel to the vas deferens for storage.
Ans. False. Immature sperms travel to the Epididymis for storage.
7. Spirogyra reproduces by regeneration.
Ans. False. Spirogyra reproduces by fragmentation.
8. On reaching puberty, a woman’s ovaries usually release thousands of eggs
each month.
Ans. False. On reaching puberty, a woman’s ovaries usually release one egg
each month.
9. If pollination occurs from one flower to another flower of the same plant, it
is called cross-pollination.
Ans. False. If pollination occurs from one flower to another flower of the same
plant, it is called self-pollination.
10. Carpel is the female reproductive part of a flower.
Ans. True.
11. Cloned animal has the DNA which is identical to parent DNA.
Ans. True.
12. The resemblances and the differences are due to heredity.
Ans. True.




Give scientific reasons.
1.    Atomic size increases down the group.
i.             The atomic numbers of the elements increase as we go down the group. Thus, the elements placed lower have more electrons.
ii.            To accommodate these electrons new shells are added to the atom.
iii.          These new shells take the outermost electrons farther from the nucleus causing atomic size (radius) to increase as we go down the group.

2.    Metallic character decreases from left to right in a period.
i.             Atoms of metals tend to lose electrons, whereas those of non – metals tend to gain them.
ii.            In a period, as we go from left to right, atomic number increases, increasing the number of electrons and protons.
iii.          These additional electrons are placed in the same outer shell and are strongly attracted towards the positively – charged nucleus.
iv.           This strong attraction does not allow loss of electrons, causing metallic character to decrease from left to right in a period.

3.    Elements in the same group show the same valency.
i.             Valency is the number of electrons given, taken or shared by an atom to complete its outermost shell.
ii.            All the elements in the same group have the same number of electrons in their outermost shells.
iii.          Thus, all these elements take, give or share the same number of electrons.
iv.           Hence, elements in the same group show the same valency.

4.    Grills of doors and windows are always painted before they are used.
i.             Usually grills of doors and windows are made of iron.
ii.            Iron objects get rusted on exposure to moist air.
iii.          Since air always contains moisture, iron grills get rusted.
iv.           Painting iron objects prevents rusting, hence iron grills of doors and windows are painted before they are used.

5.    Physical states of reactants and products are mentioned while writing a chemical equation.
i.             To make a chemical equation more informative, the physical states of the reactants and products are mentioned along with their chemical formulae.
ii.            The gaseous, liquid, aqueous and solid states of reactants and products are represented by the notations (g), (l), (aq) and (s) respectively.
iii.          The word aqueous (aq) is written if the reactant or product is present as a solution in water. 

6.    Potassium Ferrocyanide is stored in dark coloured bottles and kept away from sunlight.
i.             Potassium Ferrocyanide gets decomposed when exposed to bright light.
ii.            The dark colours of the bottles absorb a lot of energy from the light passing through it.
iii.          If stored in dark – coloured bottles, it does not get enough light energy to decompose.
iv.           Hence, potassium Ferrocyanide is stored in dark – coloured bottles and kept away from sunlight to prevent its decomposition.

7.    Iron articles rust readily whereas steel which is also mainly made of iron will not undergo corrosion.
i.             One of the properties of iron is that it reacts with oxygen in the presence of moisture and gets corroded by forming rust.
ii.            Air contains oxygen and moisture. Hence, iron readily rust when exposed to air.
iii.          Steel (stainless steel, not mild steel) is an alloy of iron having the property to resist corrosion including rusting.
iv.           Hence, stainless steel, though it contains iron, does not undergo corrosion.

8.    Edible oil is not allowed to stand for a long time in an iron or tin container.
i.             If edible oil is allowed to stand for a long time in an iron or tin container the fatty acids in the oil react with rust flakes or powder to form salts.
ii.            These salts contaminate the oil and hence the oil becomes rancid.
iii.          Rancid oils have a foul odour and unpleasant taste.
iv.           Thus, rancid oil is of no use. Hence, Edible oil is not allowed to stand for a long time in an iron or tin container to avoid rancidity.

9.    Edible oil is not allowed to stand for a long time in air. 
i.             When edible oils are left exposed to air for long period of time, they become rancid (i.e. the oils get oxidized.)
ii.            Rancid oils have a foul odour and unpleasant taste.
iii.          Thus, rancid oil is of no use.
iv.           Edible oil is not allowed to stand exposed to air for long to avoid rancidity.

10.The material used for fuse has low melting point.
i.             A fuse is used to protect a circuit and the appliances connected in the circuit by stopping the flow of an excess electric current. For this, a fuse is connected in series in the circuit.
ii.            When the current in the circuit passes through the fuse, its temperature increases. When the current exceeds the specified value, the fuse must melt to break the circuit. For this, the material used for a fuse has low melting point.

11.Wood and glass are good insulators.
i.             When a current flows through a conductor, the free electrons in the atoms move from one end of the conductor to the other.
ii.            Certain materials have less free electrons in their atoms and the current does not easily flow through the material.
iii.          There are no such free electrons in wood and glass. Hence they cannot conduct electricity. Hence, they are good insulators.

12.The melting point of filament of a bulb is very high.
i.             The bulb begins to glow only when the filament is heated to a high temperature, and it becomes incandescent (bright) without melting.
ii.            This happens only when the material of the filament has a high melting point.
iii.          Hence, the material used in the filament of an electric bulb must have a high melting point. For eg. Tungsten (33800C)

13.Connecting wires in a circuit are made of copper and aluminium.
i.             Copper and aluminium offer a low resistance to the flow of current and hence they are good conductors of electricity.
ii.            Copper and aluminium are highly ductile and hence can be used for preparing the wire.
iii.          Copper being more ductile, it is used in making thin wires, and aluminium is used for making thicker wires.
iv.           Thus, they are suitable for making wires used in electrical circuit.

14.Wires carrying electricity should not be touched bare footed.

i.             Our body is a good conductor of electricity.
ii.            If we touch the wire bare footed, a large current may pass through our body.
iii.          Due to this, we may receive severe electric shock and sometimes even death.
iv.           Therefore, wires, carrying electricity should not be touched bare footed.

15.We should not use many electrical appliances simultaneously.
i.             Many of the electrical appliances that we use at home have a high power rating. E.g. grinder, A.C, Oven, washing-machine, etc.
ii.            When we use these electrical appliances simultaneously, it causes overloading, that is flow of large amount of current in the circuit, occurs.
iii.          This causes fire.
iv.           Hence, we should not use many electrical appliances simultaneously.

16.Alloys like alnico or nipermag are used in industry.
i.             Alloys like alnico or nipermag are very hard and are used in the production of permanent magnets.
ii.            Permanent magnets of these alloys are used in microphones, loudspeaker, ammeters, voltmeters, etc.
iii.          Alnico is an alloy of iron containing aluminium, nickel and cobalt. Nipermag is an alloy of iron containing nickel, aluminium and titanium.
iv.           Hence, permanent magnets prepared from these alloys are most suitable for use in industries.

17.A magnetic crane is used to load and transport scrap iron.
i.             It is not feasible to create a permanent magnet of a big size required to load and transport scrap iron.
ii.            It is also not possible to store such a big magnet.
iii.          Hence, we create a powerful electromagnet by passing a current through a big iron disc.
iv.           Therefore, a magnetic crane is used to load and transport scrap iron.

18.You cannot enjoy watching a movie from a very short distance from the screen in a cinema hall.
i.             If the object is too close, the eye lens cannot curve enough to focus the image on to the retina.
ii.            Therefore, while watching a movie from a very short distance a blurred image is formed causing strain to the eyes.
iii.          Hence, one cannot enjoy watching a movie from a very short distance from the screen in a cinema hall.

19.A simple microscope is used by watch repairers.
i.             A magnification of about 20 times is obtained by the convex lens of small focal length used in a simple microscope.
ii.            Therefore, it is used by watch repairers to see the minute parts of the watch clearly without causing any strain to the eyes.

20.A concave lens is used to correct myopia.
i.             In myopia the image of distant object is formed in front of retina.
ii.            A concave lens causes light rays to diverge before they strike the lens of the eye so that the image is formed on the retina.
iii.          Hence, a concave lens is used to correct myopia.

21.In old age bifocal lens is necessary for some persons.
i.             In old age, sometimes person suffers both myopia and hypermetropia and then the person needs bifocal lens.
ii.            In bifocal lens, upper part is concave lens to correct myopia and lower part is convex lens to correct hypermetropia.

22.Concave mirrors are used in solar devices.
i.             Concave mirrors are used in solar devices to collect heat and radiations.
ii.            Heat radiations from the sun coming from infinity are brought to focus by concave mirror in its focal plane.

23.  The sky appears dark instead of blue to a person located in space.
i.             At very high altitudes, there is no atmosphere.
ii.            Since there is no atmosphere, the scattering of light does not take place at all.
iii.          Hence, the sky appears dark instead of blue to a person located in space.

24.Stars twinkle at night.

i.             The stars emit their own light and they shine at night. The stars are point sources of light as they are very far away.
ii.            During refraction of starlight from the atmosphere, as starlight bends towards the normal, the apparent position of the star is slightly higher than its actual position.
iii.          Also this apparent position of the star is not stationary but changes slightly.
iv.           Because of mobility of air and changes in the temperature, the atmosphere is not steady. Hence refractive index of air in the given region goes on changing continuously and randomly.
v.             When the atmosphere refracts more light towards us, the star is seen bright. When the atmosphere refracts less light towards us, the star is seen dim. Thus due to change in the refractive index of atmosphere, stars appear twinkling at night. 

25.The sun appears reddish early in the morning.
i.             At the time of sunrise, the blue and violet colours are scattered away from the path of sunlight as thickness of the atmosphere is more between the horizon and the observer.
ii.            The light that reaches to the observer is mostly red.
iii.          Hence the sun appears reddish early in the morning.

26.  It is possible to enjoy a rainbow at fountains in any season.
i.             One can observe and enjoy the rainbow by standing in front of a water fountain in the evening facing the east.
ii.            One can also enjoy it in the morning under the same conditions just by facing the west.
iii.          Therefore, it is possible to enjoy a rainbow at fountains in any season.
27.  Sodium is stored under kerosene.
i.             Sodium is a highly reactive metal.
ii.            Sodium reacts with oxygen in air at room temperature to form, sodium oxide.
iii.          Therefore, it catches fire and starts burning when open in the air.
iv.           Hence, sodium is stored under kerosene to prevent its reaction with oxygen, moisture and carbon dioxide.

28.Gold and silver are used to make jewellery.
i.             Gold and silver are highly inactive metals. Therefore, they do not undergo corrosion due to attack by moisture and atmospheric gases.
ii.            Gold and Silver are very shiny metals (lustrous).
iii.          They are used to make jewellery because of its bright shiny surface and high resistance to corrosion.

29.Calcium floats over water during the reaction with water.
i.             Calcium reacts with water less vigorously so that the heat evolved is not sufficient for the hydrogen formed, to catch fire.
ii.            Instead, calcium starts floating because the bubbles of hydrogen gas formed stick to the surface of the water calcium.

30.Ionic compounds have high melting and boiling points
i.             Ionic compounds are solids and hard due to strong force of attraction between positive and negative ions in their molecules.
ii.            A considerable amount of energy is required to break the strong inter molecular attraction.
iii.          Hence ionic compounds have high melting and boiling points.

31.Tarnished copper utensils are cleaned with lime juice or tamarind.
i.             When copper utensils are exposed to moist air, they get tarnished or corroded due to the formation of green copper carbonate.
ii.            When these tarnished vessels are rubbed with lime juice or tamarind the weak acids present in them dissolve the green copper carbonate and original shine returns.

32. Breathing rate increases during vigorous exercising.
i.             The living body requires constant supply of energy.
ii.            This energy in the form of ATP is released through oxidation of glucose in each cell.
iii.          For this oxidation, constant supply of oxygen is needed which is obtained through breathing.
iv.           When vigorous exercise is done, there is more need of ATP and thus more oxygen is required for the cellular respiration.
v.             To make available to this increased demand the breathing rate increases during vigorous exercising.

33. Translocation is needed in all higher plants.
i.             Transport of nutrients from leaves to other parts of the plant is termed translocation.
ii.            Higher plants bear roots, leaves, flowers, fruits and seeds. These part of plants need food for carrying out their various metabolic activities.
iii.          The amino acids, sugar and starch are stored in fruits and seeds for future use.
iv.           Thus, translocation is needed in higher plants.

34. The plants are kept in dark before determining the factors essential for photosynthesis.
i.             When plants perform photosynthesis, they produce carbohydrates. These carbohydrates are used for their growth and energy.
ii.            The unutilized carbohydrates are stored in the form of starch.
iii.          While performing experiments on photosynthesis, it is necessary that this stored starch is completely used up.
iv.           When the plant is kept in dark, it utilizes this stored starch and becomes destarched.
v.             The factors essential for photosynthesis such as carbon dioxide, sunlight and chlorophyll can be studied with such destarched plant. Thus, the plants are kept in dark before determining the factors essential for photosynthesis.   

35. It is necessary to separate oxygenated blood from the deoxygenated blood in mammals.
i.     Mammals require constant supply of energy to maintain their high body temperature.
ii.    Due to this they have high energy need. This energy is supplied through oxygen rich blood.
iii.  Therefore oxygenated and deoxygenated blood should not mix with each other.
iv.   In mammals heart, these two types of bloods are separated by the septum in the heart and thus they have highly efficient supply of oxygen to the body.  

36.  Roots of plants grow away from light.
i.             The root system of plants always grows downwards in response to the stimulus of gravity and water.
ii.            This makes sure that the roots will find soil and water.
iii.          Hence, the roots of plants grow away from light.

37. Hormones secreted by the endocrine glands are present everywhere in the body.
i.             Endocrine glands do not have ducts to store or transport their secretions called hormones.
ii.            The hormones are directly released into the blood stream and reach concerned body parts through blood.
iii.          Hence, hormones secreted by the endocrine glands are present everywhere in the body.

38. Insulin plays an important role in controlling the sugar level of blood.
i.             When the sugar level of the blood rises, it is detected by the cells of the pancreas which respond to the situation by producing more insulin.
ii.            As the sugar level of the blood falls, the secretion of insulin is reduced.
iii.          Thus, insulin plays an important role in controlling the sugar level of blood.

39.  In sexual mode of reproduction greater diversities are generated.
i.             In sexual mode of reproduction two parents are involved.
ii.            Each one has its own DNA copies that are passed on through their nuclei at the time of fertilization of gametes.
iii.          Therefore more diversity is produced.
iv.           Moreover, the process of meiosis at the time of gamete formation, also produces variations. Hence in sexual mode of reproduction greater 
40. Phenotypic and genotypic ratios are different.
i.             Phenotype is the appearance or any detectable characteristic feature of an individual life red and white flowers.
ii.            Genotype is the genetical composition of individuals like RR, Rr and rr.
iii.          Hence, phenotypic and genotypic ratios are different. 

41. In human beings the gametes from the male parent decides the sex of the baby.

i.             In human male gametes, two dissimilar chromosomes XY are present whereas in females two similar chromosomes XX are present.
ii.            All children inherit ‘X’ chromosomes from their mother and ‘X’ or ‘Y’ from their father.
iii.          Hence the gametes from the male parent decide the sex of the baby.

42. Paleontological evidence suggests that invertebrates came into existence before the vertebrates.
i.             A systematic study of fossils and its occurrence revealed that the deepest layers of land were found to have fossils of invertebrates.
ii.            In layers above them were found vertebrates such as fish – like animals, amphibians, reptiles, birds and mammals.
iii.          This suggests that invertebrates came into existence before the vertebrates.


Answer the following
1.    How could the modern periodic table remove various anomalies of Mendeleev’s periodic table?
Ans.
i.         A periodic table is a tabular arrangement of elements such that the elements can be classified on the basis of their common properties.
ii.       Properties of elements are related to their electronic configuration which in turn depends on their atomic numbers.
iii.     In the modern periodic table, the elements are arranged in the ascending order of their atomic numbers such that the elements having similar properties fall in the same group.
iv.      This arrangement removed various anomalies of Mendeleev’s periodic table which depended on atomic masses of the elements.

2.    In modern periodic table, which are the metals, non metals and metalloids among the first 20 elements?
Ans.  In the modern periodic table, among the first 20 elements, following are the metals, non – metals and metalloids.
Metals
Non  metals
Metalloids
Lithium (Li)
Beryllium (Be)
Sodium (Na)
Magnesium (Mg)
Aluminium (Al)
Potassium (K)
Calcium (Ca)
Hydrogen (H)
Helium (He)
Carbon (C)
Nitrogen (N)
Oxygen (O)
Fluorine (F)
Neon (Ne)
Phosphorus (P)
Sulphur (S)
Chlorine (Cl)
Argon (Ar)
Boron (B)
Silicon (Si)

3.    What are the demerits of Mendeleev’s periodic table?
Ans.
i.             Hydrogen resembles alkali metals as well as halogens. Therefore, no fixed position could be given to hydrogen in the periodic table.
ii.            Isotopes of same elements have different atomic masses; therefore each one of them should be given a different position. On the other hand as isotopes are chemically similar, they had to be given same postion.
iii.          At certain places, an element of higher atomic mass has been placed before an element of lower mass. For example, cobalt (Co = 58.93) is placed before nickel (Ni = 58.71).
iv.           Some element placed in the same sub group had different properties, e.g. Mangenese (Mn) is placed with halogens which totally differ in the properties. 

4.    Define atomic size. How does it vary in a period and in a group?
Ans.
i.             Atomic size is determined by using atomic radius.
ii.            For an isolated atom, its atomic radius is the distance between the centre of the atom (i.e. centre of its nucleus) and its outermost shell.
iii.          In a period, atomic radius generally decreases from left to right. This is because the electrons are added to same shell and experience greater pull from the nucleus.
iv.           Atomic radius increases in a group from top to bottom as new shells are added bringing outermost electrons farther from the nucleus.