Question

$0.60$ g of gaseous oxide of sulphur was found to occupy a volume of $40c{m}^3$ at STP. What will be the molecular mass of oxide?

• A. $342$
• B. $335$
• C. $268$
• D. $120$

Answer 1

The correct option is B $335$

At S.T.P, 1 mole of any gas occupies a volume of 22.4 L or 22400 $c{m}^3$.

Volume of gaseous oxide of sulphur is $40c{m}^3$

The number of moles of gaseous oxide of sulphur $=\frac{40c{m}^3}{22400c{m}^3}=0.00179$ mol.
The mass of gaseous oxide of sulphur is 0.60 g.

The molecular mass of 1 mole of gaseous oxide of sulphur will be $\frac{0.60g}{0.00179mol}=335g$