1. 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) |