Question

Two solid compounds ${}^{\prime }{X}^{\prime }$ and ${}^{\prime }{Y}^{\prime }$ dissociates at certain temperature as follows:
$X\left(s\right)\rightleftharpoons A\left(g\right)+2b\left(g\right)K{p}_1=9\times {10}^{-3}{\text{atm}}^3$
$Y\left(s\right)\rightleftharpoons 2B\left(g\right)+C\left(g\right)K{p}_2=4.5\times {10}^{-3}{\text{atm}}^3$.
The total pressure (in atm) of gases over a mixture of ${}^{\prime }{X}^{\prime }$ and ${}^{\prime }{Y}^{\prime }$ is

• A. 1.5
• B. 0.45
• C. 0.6
• D. 0.9

Answer 1

The correct option is B 0.45

Let
X gives a moles of A and 2a moles of B
Y gives b moles of C and 2b moles of B
then,
$K_{p1}=P_a(2P_a+2P_b{)}^2=0.009$
$K_{p2}=P_b(2P_a+2P_b{)}^2=0.0045$

$\therefore$ $\frac{P_a}{P_b}=2$
$P_a=2P_b$
so
$P_a(2P_a+P_a{)}^2=0.009$
$9P_a^3=0.009$
$P_a=0.1$
$P_b=0.05$
$totalpressure=3P_a+3P_b=0.45$