Non-metals Class 10th Science Gujarat Board Solution

Class 10th Science Gujarat Board Solution
Exercise
  1. Which non-metallic element is in liquid form?A. Carbon B. Hydrogen C. Bromine D.…
  2. With which of the following elements carbon does not give reaction?A. Dichloride gas B.…
  3. Which of the following oxides is of neutral nature?A. CO2 B. SO2 C. P2O5 D. N2O…
  4. Which of the following gases is insoluble in water ?A. NH2 B. SO2 C. H2 D. CO2…
  5. Which of the following acids is called king of chemicals ?A. HNO3 B. H2SO4 C. HCl D.…
  6. Which of the following gases is combustible ?A. CO2 B. H2 C. SO2 D. NH3…
  7. Which of the following acts as catalyst in production of ammonia by Haber’s process?A.…
  8. Make the correct pairs from below mentioned (X) and (Y). A. (a-4) (b-3), (c-2). (d-1) B.…
  9. Make correct pairs from below mentioned (X) and (Y). A. (a-4), (b-3), (c-1), (d-2) B.…
  10. Make the correct pairs from below mentioned (X) and (Y) A. (a-2). (b-3), (c-1), (d-4) B.…
  11. Give two examples of non-metallic elements which are in solid form.…
  12. Give two examples of non-metallic elements which are in gaseous form.…
  13. The mixture of which two gases is known as water gas?
  14. Which two substances are used as promoters in manufacture of ammonia gas by Haber’s…
  15. What is meant by liquor ammonia? Write its chemical formula.
  16. What is meant by allotropy and allotropes?
  17. Write two allotropes of sulphur.
  18. Mention the effect of litmus paper on aqueous solution of ammonia.…
  19. Mention the formulas of the products, name and physical state of the following reactions:…
  20. Mention the missing information in In the following chemical reactions: (i) + H2O(l)…
  21. Mention physical properties of non-metallic elements.
  22. Mention physical properties of dihydrogen gas.
  23. Write uses of dihydrogen gas.
  24. Write physical properties of ammonia gas.
  25. Write chemical equations, to obtain nitric acid from ammonia gas by Ostwald’s process.…
  26. Write uses of ammonia gas.
  27. Mention physical properties of sulphur.
  28. Mention the chemical reactions of sulphur with acids, dihydrogen gas and carbon element.…
  29. Mention uses of sulphur.
  30. Write physical properties of sulphur dioxide gas.
  31. Mention uses of sulphur dioxide gas.
  32. Write uses of sulphuric acid.
  33. Give difference between concentrated sulphuric acid and dilute sulphuric acid.…
  34. Explain with diagram the method for preparation of hydrogen gas in laboratory.…
  35. Explain with chemical equations the industrial production of dihydrogen gas.…
  36. Discuss Haber’s process for industrial manufacture of ammonia.
  37. Write short note: Allotropes of sulphur.
  38. Explain contact process for production of sulphuric acid.
  39. Explain chemical properties of dilute sulphuric acid.
  40. Explain chemical properties of non-metallic elements.
  41. Explain chemical properties of dihydrogen gas.
  42. Describe Frasch’s method of extraction of sulphur.
  43. Discuss chemical properties of sulphur dioxide gas.

Exercise
Question 1.

Which non-metallic element is in liquid form?
A. Carbon

B. Hydrogen

C. Bromine

D. Phosphorus


Answer:

The only non-metal that is in liquid form at room temperature is bromine.

Carbon and phosphorus are the examples of non-metals in solid form. Hydrogen is an example of a gaseous non-metallic element.


Question 2.

With which of the following elements carbon does not give reaction?
A. Dichloride gas

B. Dioxygen gas

C. Dihydrogen gas

D. Dilute hydrochloric acid


Answer:

Carbon does not react with dilute hydrochloric acid because:

i. Carbon is a non-metal.


ii. Non-metals are electron acceptors.


iii. Hence, they are not able to remove the hydrogen present in acids.


iv. Thus, the effect of dilute hydrochloric acid on carbon is not observed.


Question 3.

Which of the following oxides is of neutral nature?
A. CO2

B. SO2

C. P2O5

D. N2O


Answer:

Among the given oxides, N2O is of neutral nature:

i. When non-metal combines with oxygen, it forms oxide.


ii. A neutral oxide is an oxide which neither reacts with an acid nor with a base.


iii. Nitrous oxide (N2O) is an example of neutral oxide (an oxide which is neutral in nature)


iv. Other examples of neutral oxides are H2O and CO (carbon monoxide).


Question 4.

Which of the following gases is insoluble in water ?
A. NH2

B. SO2

C. H2

D. CO2


Answer:

Dihydrogen gas (H2) is insoluble in water whereas carbon dioxide, sulphur dioxide and ammonia are soluble in water.


Question 5.

Which of the following acids is called king of chemicals ?
A. HNO3

B. H2SO4

C. HCl

D. CH3COOH


Answer:

Sulphuric acid is called king of chemicals because:

i. It is a very important industrial chemical.


ii. It is widely used to prepare other chemicals.


iii. It is used in the production of fertilizers, paints, soaps, detergents, synthetic fibres etc.


Question 6.

Which of the following gases is combustible ?
A. CO2

B. H2

C. SO2

D. NH3


Answer:

Dihydrogen gas is combustible. It is very stable and it reacts with air without burning.


Question 7.

Which of the following acts as catalyst in production of ammonia by Haber’s process?
A. Al2O3

B. K2O

C. V2O5

D. Fe


Answer:

Haber’s process:

i. Production of ammonia gas is carried out by Haber’s process.


ii. In this process, dihydrogen and dinitrogen are mixed together.


iii. They are passed over iron (Fe) catalyst to form ammonia.


iv. The reaction takes place given below:



Note: A catalyst is a substance which can change the speed of reaction without itself undergoing any change.


Question 8.

Make the correct pairs from below mentioned (X) and (Y).


A. (a-4) (b-3), (c-2). (d-1)

B. (a-2) (b-4), (c-1), (d-3)

C. (a-3), (b-2), (c-4), (d-1)

D. (a-4), (b-2), (c-3), (d-1)


Answer:

(a-2) Extraction of sulphur is done by Frasch method

(b–4) Production of nitric acid is done by Ostwald’s method.


(c-1) Production of sulphuric acid is done by the Contact process


(d-3) Production of ammonia gas is done by Haber’s Process.


Question 9.

Make correct pairs from below mentioned (X) and (Y).


A. (a-4), (b-3), (c-1), (d-2)

B. (a-3), (b-2), (c-4), (d-1)

C. (a-3), (b-1), (c-2), (d-4)

D. (a-2), (b-4), (c-1), (d-3)


Answer:

(a – 2)

Sulphuric acid is a strong dehydrating agent.


i. It means sulphuric acid has a property to remove water from any substance.


ii. For example: If sulphuric acid falls on sugar, paper, wood etc., it removes water from it and burns it.


iii. Hence, utmost care is taken while using it.


(b – 4)


Sulphur is used in the preparation of fire crackers.


(c – 1)


Sulphur is used in the bleaching of wooden pulp in the paper industry. Thus, it is a weak bleaching agent.


(d – 3)


Dihydrogen (H2) gas is much lighter than air and also lighter than all other gases. So, it is the lightest gas among all.


Question 10.

Make the correct pairs from below mentioned (X) and (Y)


A. (a-2). (b-3), (c-1), (d-4)

B. (a-4), (b-2), (c-1), (d-3)

C. (a-3), (b-4), (c-2), (d-1)

D. (a-2), (b-3), (c-1), (d-4)


Answer:

(a-3)

The chemical formula of sulphurous acid is H2SO3.


The structure of sulphurous acid is:



(b-4)


The chemical formula of sulphuric acid is H2SO4.


The structure of sulphuric acid is:



(c-2)


Oleum is also known as fuming sulphuric acid. The chemical formula of oleum is H2S2O7.


The structure of oleum is:



(d-1)


The chemical formula of phosphoric acid is H3PO4.


The structure of phosphoric acid is:



Question 11.

Give two examples of non-metallic elements which are in solid form.


Answer:

Two examples of non-metallic elements which are in solid form are:

i. Carbon


ii. Sulphur




Question 12.

Give two examples of non-metallic elements which are in gaseous form.


Answer:

Two examples of non-metallic elements which are in gaseous form are:

i. Hydrogen


ii. Oxygen


Note: Some other examples of non-metals in gaseous form are nitrogen, chlorine etc.



Question 13.

The mixture of which two gases is known as water gas?


Answer:

The gaseous mixture of carbon monoxide and dihydrogen gas is known as water gas.



Question 14.

Which two substances are used as promoters in manufacture of ammonia gas by Haber’s process?


Answer:

Two substances which are used as promoters in manufacture of ammonia gas by Haber’s process are:

i. Aluminium oxide (Al2O3)


ii. Potassium oxide (K2O)


They are added to increases the efficiency of the catalyst. Hence, they are called promoters.



Question 15.

What is meant by liquor ammonia? Write its chemical formula.


Answer:

The concentrated solution of ammonia is called liquor ammonia. The chemical formula of liquor ammonia is NH4OH.



Question 16.

What is meant by allotropy and allotropes?


Answer:

Some elements exist in two or more forms having different physical properties (different arrangement of atoms) and same chemical properties. This property of an element is called allotropy.

The allotropic forms of that element are called allotropes.



Question 17.

Write two allotropes of sulphur.


Answer:

There are two allotropic forms of sulphur which are:

i. Rhombic sulphur- It is stable at temperature lower than 369K and has an octahedral structure.



ii. Monoclinic sulphur - It is stable at temperature higher than 369K and has a needle like structure.




Question 18.

Mention the effect of litmus paper on aqueous solution of ammonia.


Answer:

The effect of litmus paper on aqueous solution of ammonia:

i. Dry ammonia gas does not show any effect on litmus paper.


ii. But aqueous solution turns red litmus paper into blue.


iii. This indicates that aqueous solution of ammonia shows basic nature.



Question 19.

Mention the formulas of the products, name and physical state of the following reactions:

i. P4(s) + 502(g)  ........................

ii. SO2(g) + H2O(l)  ........................

iii. P4(s) + 6Cl2(g)  ........................

iv. O2(g) + 2H2(g)  ........................

v. Mg(s) + H2O(g)  ........................

vi. 3Fe(s) + 4H2O(g)  ......................

vii. CO (g) + H2O(g)  .......................

viii. 3NO2 (g) +H2O(l)  .......................

ix. S(s) +6HNO3(aq)  .......................

x. SO3(g) + H2SO4(aq)  .......................

xi C12H22O11(s)+ Con H2SO4(l)  ..............

xii CaCO3(s) + dil H2SO4(aq)  ..............


Answer:

i. P4(s) + 5O2(g) → P4O10(s)


It is a reaction in which non-metallic element combines with dioxygen gas to form oxide.


ii. SO2(g) + H2O(l) → H2SO3 (l)


This is a type of synthesis reaction. This reaction is used in the preparation of sulphurous acid


iii. P4(s) + 6Cl2(g) → 4PCl3(g)


The above reaction is a type of synthesis reaction. This reaction is used in the preparation of phosphorus trichloride.


iv. O2(g) + 2H2(g) → 2H2O (l)


It is a reaction in which non-metallic element reacts with dihydrogen gas to form stable hydride compounds.


v. Mg(s) + H2O(g) → MgO (s) + H2 (g)


It is a reaction in which a less active metal reacts with water to form dihydrogen gas. The other less active metals are zinc and iron.


vi. 3Fe(s) + 4H2O(g) → Fe3O4(s) + 4H2(g)


It is also a reaction in which a less active metal reacts with water to form dihydrogen gas.


vii. CO (g) + H2O(g) → CO2 (g) + H2 (g)


This is a reaction in which mixture of water gas (CO2 and H2) is passed with water vapour to produce excess dihydrogen gas and to remove carbon monoxide.


viii. 3NO2 (g) +H2O(l) → 2HNO3 (l) + NO(g)


The above reaction is a part of Ostwald process.


ix. S(s) +6HNO3(aq) → H2SO4(aq) + 6NO2(g) + 2H2O(l)


It is a reaction in which sulphur reacts with nitric acid to form sulphuric acid, nitrogen dioxide and water.


x. SO3(g) + H2SO4(aq) → H2S2O7(l)


The above reaction is a type of synthesis reaction. This reaction is used in the preparation of oleum (H2S2O7) which is also known as fuming sulphuric acid.


xi. C12H22O11(s)+ Con H2SO4(l) → 12C (s) +11H2O(l)


The above reaction is a type of dehydration reaction. The sulphuric acid acts as a dehydrating agent. It removes the water from sugar (C12H22O11) and burn it.


xii. CaCO3(s) + dil H2SO4(aq) → CaSO4(aq) + CO2(g) + H2O(l)


The above reaction is a type of dehydration reaction. The sulphuric acid will act as a dehydrating agent. It produces calcium sulphate, carbon dioxide and water.



Question 20.

Mention the missing information in  In the following chemical reactions:

(i)  + H2O(l) H2SO4(aq)

(ii). S(s) +  SO2(g)

(iii).  + H2O(l H2CO3(aq)

(iv). S(s) + H2(g) 

(v). 2Na(s) + 2NaOH(aq) + H2(g)

(vi). Zn(s) + H2O(g) → ZnO(s) + 

(vii). CH4(g) + H2O(g) CO(g) + 3H2(g)

(viii). CuO(s) + Cu(s) + H2O(g)

(ix). H2(g) + 2KH(s)

(x). MgSO4(aq) + Mg(OH)2(s) + (NH4)2SO4(aq)

(xi). SO2(g) + 2H2S(g) 3S(s) + 2H2O(g)

(xii). 2SO2(g) 2SO3(g)

(xiii). CuSO45H2O(s) + con. H2SO4(l)


Answer:

(i) SO3(g) + H2O(l) H2SO4(aq)


Sulphur trioxide gas reacts with water to form sulphuric acid with very corrosive fumes.


(ii) S(s) + O2(g) → SO2(g)


Sulphur reacts with dioxygen gas to form sulphur dioxide (non-metallic oxide). This oxide is acidic in nature.


(iii) CO2 + H2O(l H2CO3 (aq)


Carbon dioxide reacts with water to form carbonic acid (H2CO3). This means carbon dioxide is an acidic oxide i.e., an oxide which is acidic in nature.


(iv) S(s) + H2(g) → H2S (g)


Sulphur (non-metallic element) reacts with dihydrogen gas to form hydrogen sulphide that is a stable hydride compound.


(v) 2Na(s) + 2H2O (l) → 2NaOH(aq) + H2(g)


When active metal like Na reacts with water, it produces sodium hydroxide and liberates dihydrogen gas.


(vi) Zn(s) + H2O(g) → ZnO(s) + H2(g)


Less active metal like Zn reacts with water vapour to form zinc oxide and dihydrogen gas.


(vii) 


In this process, methane mixed with water over nickel catalyst to form a mixture of carbon monoxide and dihydrogen gas.


This mixture is called water gas.


(viii) CuO(s) + H2(g) → Cu(s) + H2O(g)


Dihydrogen gas is a good reducing agent. It reduces easily the metallic oxides.


(ix) H2(g) + 2K(s) → 2KH(s)


When dihydrogen gas reacts with metal, it forms the metallic hydride of that element.


(x) MgSO4(aq) + NH4OH (aq) → Mg(OH)2(s) + (NH4)2SO4(aq)


Ammonium hydroxide (NH4OH) forms magnesium hydroxide (Mg(OH)2)


(xi). 


SO2 reacts with H2S in the presence of Fe2O3 catalyst to form


sulphur. It is one of the methods for the extraction of sulphur.


(xii). 


On reaction of sulphur dioxide gas with dioxygen gas in the presence of vanadium catalyst (V2O5), sulphur trioxide gas is formed.


(xiii) CuSO45H2O(s) + con. H2SO4(l) → CuSO4


Addition of sulphuric acid to copper sulphate, the water is removed. Because sulphuric acid is a dehydrating agent. It removes all the water present in the substance.



Question 21.

Mention physical properties of non-metallic elements.


Answer:

Physical properties of non-metallic elements are:

i. They are non-lustrous except iodine which is lustrous in appearance.


ii. They are brittle, hard or soft.


iii. They are poor conductors of electricity except graphite which is a good conductor of electricity.


iv. They combine with oxygen to form metallic oxides.


v. Metallic oxides are either acidic or neutral in nature.



Question 22.

Mention physical properties of dihydrogen gas.


Answer:

Physical properties of dihydrogen gas are:

i. It is colourless, odourless and tasteless gas.


ii. It is insoluble in water.


iii. It is much lighter than air and also lighter than all other gases.


iv. Hence, it is the lightest gas.


v. It is a neutral gas.



Question 23.

Write uses of dihydrogen gas.


Answer:

Uses of dihydrogen gas are:

i. It is used in the production of ammonia in Haber’s process.


ii. It is used in welding of metals.


iii. It is used as fuel in rockets.


iv. It is also used as fuel cell for the production of electricity.


v. It is an important source of energy in future.



Question 24.

Write physical properties of ammonia gas.


Answer:

Physical properties of ammonia gas are:

i. It is a colourless gas.


ii. It is lighter gas than air.


iii. It gets completely dissolve in water this means it is highly soluble in water.


iv. It has a very unpleasant smell which can cause irritation to eyes and nose.


v. Aqueous solution of ammonia acts as a weak base.



Question 25.

Write chemical equations, to obtain nitric acid from ammonia gas by Ostwald’s process.


Answer:

Ostwald’s process:

i. Ammonia gas is used in the preparation of nitric acid by this method.


ii. First, ammonia and dioxygen gas react together over platinum catalyst to form nitric oxide (NO)



iii. Now, nitric oxide formed above combines with oxygen to form fumes of nitrogen dioxide (NO2)


2NO + O2→ 2NO2


iv. The nitrogen dioxide reacts with water to form nitric acid.


NO2 + H2O → HNO3


Nitric acid



Question 26.

Write uses of ammonia gas.


Answer:

Uses of ammonia gas:

i. It is used in the preparation of baking soda and washing soda.


ii. It is used in the preparation of nitric acid by Ostwald’s method.


iii. The important use of ammonia is that; it is used in the preparation of number of fertilizers.


iv. It is used to prepare dyes, explosives etc.


v. It is also used in the preparation of medicines like folic acid etc.



Question 27.

Mention physical properties of sulphur.


Answer:

Physical properties of sulphur:

i. It is a yellow coloured solid substance.


ii. It has two allotropes which are rhombic sulphur and monoclinic sulphur.


iii. It is insoluble in water.


iv. But it is soluble in organic solvents like carbon disulphide, toluene, ethanol etc.


v. It has low melting point.



Question 28.

Mention the chemical reactions of sulphur with acids, dihydrogen gas and carbon element.


Answer:

Reactionof sulphur with acids:


i. Sulphur reacts with hot concentrated sulphuric acid to form sulphur dioxide. The reaction is:


S + 2H2SO4→ 2H2O + 3SO2


ii. Sulphur reacts with concentrated nitric acid to form sulphuric acid. The reaction is:


S + 6HNO3→ H2SO4→ 6NO2 + 3H2O


Reactionof sulphur with dihydrogen gas (H2):


Sulphur reacts with dihydrogen gas to form hydrogen sulphide. The reaction is:


S + 2H2→ 2H2S


Reaction with carbon element:


Sulphur reacts carbon element to form carbon disulphide. The reaction is:


C+ 2S → CS2



Question 29.

Mention uses of sulphur.


Answer:

Uses of sulphur are:

i. It is used in the manufacture of sulphuric acid.


ii. It is used in the production of solvent like carbon disulphide (CS2)


iii. It acts as an antiseptic for skin disease.


iv. It is used in the preparation of fire crackers.


v. It is also used in the preparation of insecticides.



Question 30.

Write physical properties of sulphur dioxide gas.


Answer:

Physical properties of sulphur dioxide gas are:

i. It is a colourless gas.


ii. It has unpleasant smell that causes coughing and suffocation.


iii. It is an oxide of non-metals that is sulphur.


iv. It is acidic in nature.


v. It is highly toxic and non-inflammable gas.



Question 31.

Mention uses of sulphur dioxide gas.


Answer:

Uses of sulphur dioxide gas are:

i. It is used in the manufacture of sulphuric acid.


ii. It is a weak bleaching agent.


iii. It prevents the growth of bacteria.


iv. Hence, it is used as an antiseptic.


v. It is also used as a preservative in fruits juice, in jam and drying of fruits.



Question 32.

Write uses of sulphuric acid.


Answer:

Uses of sulphuric acid:

i. It is used in identification of organic compounds in labs.


ii. It is used in the production of fertilizers.


iii. It is also used in the production of daily thig we use which are plastic, fibre, dyes, paints, detergents etc.


iv. It is used to prepare HCl, HBr from their salts.


v. It is also used to prepare explosives and drugs.



Question 33.

Give difference between concentrated sulphuric acid and dilute sulphuric acid.


Answer:

Difference between concentrated sulphuric acid and dilute sulphuric acid:




Question 34.

Explain with diagram the method for preparation of hydrogen gas in laboratory.


Answer:

The hydrogen gas can be prepared by the reaction of metal with dilute acid or water.

Preparation of hydrogen gas from zinc metals with dilute acid:


i. In labs, pieces of zinc metals are taken in a flask.


ii. Dilute sulphuric acid or dilute hydrochloric acid is added to the flask.


iii. When the reaction takes place, a solution of zinc sulphate is formed and hydrogen gas is produced. The reaction is:


Zn + H2SO4→ ZnSO4 + H2


iv. The gas formed is collected in a jar by downward displacement of water.


v. Because H2 is a gas lighter than air.




Question 35.

Explain with chemical equations the industrial production of dihydrogen gas.


Answer:

Industrial production of dihydrogen gas:

i. In industries, the production of gas is carried out from methane (natural gas).


ii. In this process, methane mixed with water over nickel catalyst to form a mixture of carbon monoxide and dihydrogen gas.


iii. This mixture is called water gas.



iv. By reaction of water gas again with water, excess dihydrogen gas is formed and carbon monoxide is removed.


CO + H2O → CO2 + H2


v. To separate H2 gas from this mixture, it is passed through water.


vi. This way it can be collected in gas jar.



Question 36.

Discuss Haber’s process for industrial manufacture of ammonia.


Answer:

Haber’s process:

i. Production of ammonia gas is carried out by Haber’s process:


ii. In this process, dihydrogen and dinitrogen are mixed together.


iii. They are passed over iron (Fe) catalyst to form ammonia.


iv. Two substances are used as promoters which are aluminium oxide (Al2O3) and potassium oxide (K2O)


v. They are added to increases the efficiency of the catalyst. Hence, they are called promoters.


vi. By cooling the reaction mixture at temperature lower than 273K, ammonia can be separated from N2 and H2 gases.


vii. The reaction takes place given below:




Flow chartfor the manufacture of ammonia gas



Question 37.

Write short note: Allotropes of sulphur.


Answer:

Sulphur has two allotropes:

Rhombic Sulphur


i. It is stable at temperature lower than 369K.


ii. It possesses octahedral structure.


iii. It is insoluble in water but soluble to some extent in benzene and alcohol.


iv. It is quickly soluble in CS2.


Monoclinic Sulphur


i. It is stable at temperature higher than 369K.


ii. It possesses needle-like structure.


iii. It is insoluble in water.


iv. It is soluble in CS2.



Question 38.

Explain contact process for production of sulphuric acid.


Answer:

Contact process:

i. In this process, first sulphur is burnt in air to form sulphur dioxide.


S + O2→ SO2


ii. Sulphur dioxide gas with excess air is passed over V2O5


catalyst so that sulphur trioxide is formed.



iii. When sulphur trioxide is dissolved in concentrated sulphuric acid, it forms fuming sulphuric acid or oleum.


SO3 + H2SO4→ H2S2O7


Oleum


iv. Oleum is diluted with water.


v. As a result, desired concentration of sulphuric acid can be obtained.


H2S2O7 + H2O → H2SO4



Question 39.

Explain chemical properties of dilute sulphuric acid.


Answer:

Chemical properties of dilute sulphuric acid:

i. When reacted with metal, dilute sulphuric acid produces metal sulphates and hydrogen gas. For examples:




ii. When dilute sulphuric acid reacts with oxides, hydroxides or carbonates of metal, it produces metal sulphates, CO2 and water. For examples:


Oxide: ZnO + H2SO4→ ZnSO4 + H2O


Hydroxide: NaOH + H2SO4→ Na2SO4 +2H2O


Carbonate: CaCO3 + H2SO4→ CaSO4 +H2O + CO2


iii. When dilute sulphuric acid reacts with sodium carbonate and sodium bicarbonate, it forms sodium sulphate and carbon dioxide.





Question 40.

Explain chemical properties of non-metallic elements.


Answer:

Chemical properties of non-metallic elements are:

Reactionof metal with dioxygen gas:


Non-metallic elements combine with dioxygen to form oxides.


C + O2→ CO2


Carbon dioxide


S + O2→ SO2


Sulphur dioxide


i. CO2 and SO2 are acidic oxides.


ii. CO and H2O are neutral oxides.


Reactionof non-metal with acid:


i. Non-metals are electron acceptors.


ii. Hence, they are not able to remove the hydrogen present in acids.


iii. Thus, the effect of dilute hydrochloric acid on carbon is not observed.


Reactionof non-metal with dihydrogen:


Non-metallic elements react with dihydrogen gas to form stable hydride compounds.


For examples:


N2 + H2→ 2NH3


O2 + 2H2→ 2H2O


C + 2H2→ CH4



Question 41.

Explain chemical properties of dihydrogen gas.


Answer:

chemical properties of dihydrogen gas are:

Reaction with dioxygen gas:


When dihydrogen gas reacts with dioxygen gas, it forms water


2H2 + O2→ 2H2O


i. Dihydrogen gas forms an explosive mixture with dioxygen gas.


ii. A large amount of heat is produced by this reaction.


Reaction with Metal oxide:


i. Dihydrogen gas is a good reducing agent.


ii. It reduces easily the metallic oxides.


For example: CuO + H2→ Cu + H2O


Reaction with active metals:


Dihydrogen gas combines with active metals like Na, K, Ca and forms the metallic hydride of that metal.


H2 + 2Na → 2NaH


H2 + 2K → 2KH


H2 + Ca → CaH2



Question 42.

Describe Frasch’s method of extraction of sulphur.


Answer:

Frasch method:

i. Frasch method is used for the extraction of sulphur from the core of the earth.


ii. This method is based on the low melting point of sulphur.


iii. Three concentric pipes are passed below in the soil so that they touch the layer of the sulphur.


iv. Superheated water vapour is passed at 443K temperature in the soil through the outermost cylinder.


v. As a result, sulphur melts because of its low melting point.


vi. Then, air is passed through the innermost cylinder so that sulphur and water in the central cylinder come out on the surface and gets cooled.


vii. Sulphur is insoluble in water. Hence, it can easily separated from the solution.




Question 43.

Discuss chemical properties of sulphur dioxide gas.


Answer:

Chemical properties of sulphur dioxide gas are:

Reaction with gas:


i. When sulphur dioxide gas is passed through the solution of sodium hydroxide, sodium sulphite is formed.


SO2 + NaOH → Na2SO3 + H2O


Sodium


sulphite


ii. When sulphur dioxide gas is passed through the lime water, lime water becomes milky and calcium sulphite is formed.


SO2 + Ca(OH)2→ CaSO3 + H2O


LimeCalcium


watersulphite


Reaction with dioxygen gas:


When sulphur dioxide gas is passed through dioxygen gas in the presence of V2O5 catalyst, sulphur trioxide is formed.


2SO2 + O2→ 2SO3


Sulphur trioxide


Reaction with hydrogen sulphide gas (H2S) :


When sulphur dioxide gas is passed through hydrogen sulphide gas, sulphur is formed.


2SO2 + H2S → 3S + 2H2O


Sulphur


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