Question

$1litre$ of $N_2$ and $7/8$ litre of $O_2$ at the same temperature and pressure were mixed together. What is the relation between the masses of the two gases in the mixture?

• A. $M_{N_2}=3M_{O_2}$
• B. $M_{N_2}=8M_{O_2}$
• C. $M_{N_2}=M_{O_2}$
• D. $M_{N_2}=16M_{O_2}$

Answer 1

Answer: (C)

$M_{N_2}=M_{O_2}$

Using ideal gas equation,

$PV=\frac{M}{m}RT$

$P\times 1=\frac{M_{N_2}}{28}RT....\left(i\right)$

$P\times \frac{7}{8}=\frac{M_{O_2}}{32}RT....\left(ii\right)$

Dividing Eq. (i) by eq. (ii), we get

$M_{N_2}=M_{O_2}$

Hence, the correct option is $\text{C}$