(a) What do you understand by the statement that 'vapour density of carbon dioxide is 22'?

(b) Atomic mass of Chlorine is 35.5. What is it's vapour density?

(a) Vapour density of carbon dioxide is 22 implies that 1 molecule of carbon dioxide is 22 times heavier than 1 molecule of hydrogen.

(b) Vapour density = $\dfrac{\text{Molecular mass}}{2}$

Molecular mass of chlorine Cl₂ = 2Cl = 2 x 35.5 = 71 g

Substituting in formula;

Vapour density = $\dfrac{71}{2}$ = 35.5

Hence, vapour density of Chlorine atom is 35.5