States of Matter - Result Question 9

9. $\quad 0.5$ moles of gas $A$ and $x$ moles of gas $B$ exert a pressure of 200 $Pa$ in a container of volume $10 m^{3}$ at $1000 K$. Given $R$ is the gas constant in $JK^{-1} mol^{-1}, x$ is

(2019 Main, 9 Jan I)

(a) $\frac{2 R}{4-R}$

(b) $\frac{4-R}{2 R}$

(c) $\frac{4+R}{2 R}$

(d) $\frac{2 R}{4+R}$

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Answer:

Correct Answer: 9. (b)

Solution:

From the ideal gas equation,

$ p V=\Sigma n R T $

Given: $p=200 Pa, V=10 m^{3}, T=1000 K$

$ n _A=0.5 \text { moles, } n _B=x \text { moles } $

On substituting the given values in equation (i), we get