Question

The active mass of $5.6$ litres of $O_2$ at STP is:

• A. $\frac{5.6}{22.4}$
• B. $\frac{8}{5.6}$
• C. $\frac{32}{5.6}$
• D. $\frac{0.25}{5.6}$

Answer 1

The correct option is A $\frac{5.6}{22.4}$

$22.4L$ of $O_2$ at S.T.P $=2\times 16=32g$
Number of moles is $5.6L=\frac{1}{22.4}\times 5.6$
Active mass = concentration in $mol{L}^{-1}$
So, active mass $=\frac{5.6}{22.4}$