Question

Match the molecules present in set 1 with their molecular mass present in set 2.

Set 1	Set 2
a) Oxygen molecule	(i) 44
b) Carbon dioxide	(ii) 18
c) Water	(iii) 32

• A. a-(iii), b-(i), c-(ii)
• B. a-(ii), b-(i), c-(iii)
• C. a-(iii), b-(ii), c-(i)
• D. a-(i), b-(iii), c-(ii)

Answer 1

The correct option is A a-(iii), b-(i), c-(ii)

Molecular mass is the total sum of the atomic masses of the elements present in the compound.

Molecular mass of oxygen molecule (${\text{O}}_2$)
$=2\times \text{(atomic mass of oxygen)}$ = $2\times \left(16\right)=32u$

Molecular mass of carbon dioxide ($\text{C}{\text{O}}_2$)
$=2\times \text{(atomic mass of oxygen)+}$ $1\times \text{(atomic mass of carbon)}$ $=2\times \left(16\right)+1\times \left(12\right)=44u$

Molecular mass of water (${\text{H}}_2\text{O}$)
$=2\times \text{(atomic mass of hydrogen)}+$ $1\times \text{(atomic mass of oxygen)}$ $=2\times \left(1\right)+16=18u$

Hence, the molecular mass of oxygen molecule is $32$, the molecular mass of carbon dioxide is $44$ and the molecular mass of water is $18$.