$10 \%$ of $PCl_5$ decomposes at a definite temperature and $4 \ atm$ pressure. At the same temperature,if $20 \%$ of $PCl_5$ decomposes,find the pressure. (Temperature remains constant.) (in $atm$)

At $500 \ K$,for a reversible reaction $A_{2(g)} + B_{2(g)} \rightleftharpoons 2 AB_{(g)}$ in a closed container,$K_C = 2 \times 10^{-5}$. In the presence of a catalyst,the equilibrium is attained $10$ times faster. The equilibrium constant $K_C$ in the presence of a catalyst at the same temperature is:

One mole of $O_{2(g)}$ and two moles of $SO_{2(g)}$ were heated in a closed vessel of $1 \, L$ capacity at $1098 \, K$. At equilibrium,$1.6 \, moles$ of $SO_{3(g)}$ were found. The equilibrium constant $K_c$ of the reaction would be

Which of the following is correct for the equilibrium shown below?
$2CH_3COOH \rightleftharpoons (CH_3COOH)_2$
(Equilibrium constants for the reaction in water and benzene are $K_{Water}$ and $K_{Benzene}$ respectively.)

The equilibrium constants $K_{p1}$ and $K_{p2}$ for the reactions $X \rightleftharpoons 2Y$ and $Z \rightleftharpoons P + Q$ respectively are in the ratio of $1 : 9$. If the degree of dissociation of $X$ and $Z$ be equal,then the ratio of total pressures at these equilibria is:

The incorrect expression among the following is: