At a certain temperature,$2HI \rightleftharpoons H_2 + I_2$. If only $50\%$ of $HI$ is dissociated at equilibrium,the equilibrium constant $(K_c)$ is:

For the reaction $A + 2B \rightleftharpoons 2C + D$,the initial concentration of $A$ is $a$ and the initial concentration of $B$ is $1.5$ times that of $A$. If the concentrations of $A$ and $D$ are equal at equilibrium,what will be the concentration of $B$ at equilibrium?

An equilibrium shifts towards reactants at higher temperatures. Find the correct graph.

The equilibrium constants $K_{p_1}$ and $K_{p_2}$ for the reactions $X \rightleftharpoons 2Y$ and $Z \rightleftharpoons P + Q$ are in the ratio of $1 : 4$. If the degree of dissociation of $X$ is $2$ times that of $Z$,then the ratio of total pressure $(P_1 : P_2)$ at these equilibria is: (Assume degree of dissociation for both reactions are very small)

Nitric oxide reacts with $Br_{2}$ and gives nitrosyl bromide as per the reaction given below:
$2 NO_{(g)} + Br_{2(g)} \longleftrightarrow 2 NOBr_{(g)}$
When $0.087 \ mol$ of $NO$ and $0.0437 \ mol$ of $Br_{2}$ are mixed in a closed container at constant temperature,$0.0518 \ mol$ of $NOBr$ is obtained at equilibrium. Calculate the equilibrium amount of $NO$ and $Br_{2}$.

At $473 \ K$, equilibrium constant $K_{c}$ for decomposition of phosphorus pentachloride, $PCl_{5}$, is $8.3 \times 10^{-3}$. If decomposition is depicted as,
$PCl_{5(g)} \rightleftharpoons PCl_{3(g)} + Cl_{2(g)}, \Delta_{r}H^{\Theta} = 124.0 \ kJ \ mol^{-1}$
$(a)$ Write an expression for $K_{c}$ for the reaction.
$(b)$ What is the value of $K_{c}$ for the reverse reaction at the same temperature?
$(c)$ What would be the effect on $K_{c}$ if $(i)$ more $PCl_{5}$ is added $(ii)$ pressure is increased $(iii)$ the temperature is increased?