Question

A pre-weighed vessel was filled with $O_{2}$ at STP and weighed. It was then evacuated, filled with $SO_{2}$ at the same temperature and pressure and again weighed. The weight of $O_{2}$ will be

• A. the same as that of the $SO_{2}$
• B. twice as that of the $SO_{2}$
• C. half of that of the $SO_{2}$
• D. one-fourth of that of the $SO_{2}$

Answer 1

Answer: (C)

When pressure, volume and temperature all are constant.
$n_{1\left(O_2\right)} =n_{2\left(SO_2\right)}$
$\frac{\text{Weight of} O_{2}}{\text{Molecular weight of} O_{2}}$ $= \frac{\text{Weight of} SO_{2}}{\text{Molecular weight of} SO_{2}}$
Weight of $O_{2}$ = Weight of $SO_{2} \times \frac{32}{64}$
$ = \frac{1}{2} \times$ Weight of $SO_{2}$