Sand is a compound of:

1. silicon and nitrogen
2. silicon and oxygen
3. oxygen and sulphur
4. none of the above

The atomicity of ozone is:

1. 2
2. 3
3. 4
4. 8

The combining power of magnesium and oxygen is the same, i.e. 2. What will be the molecular formula of magnesium oxide ?

1. Mg₂O₂
2. MgO₂
3. Mg₂O
4. MgO

Define:

(a) Atom

(b) Molecule

(c) Atomicity

(d) Formula