For a gaseous reaction $pA + qB \rightleftharpoons qC + pD$,which of the following relationships is true?

In a $1 \ L$ closed container,$4 \ moles$ of $PCl_5$ are heated. If $80\%$ of $PCl_5$ remains undissociated at equilibrium,what is the value of the equilibrium constant $(K_c)$?

$1 \ mole$ of $HI$ is heated in a closed container of capacity $2 \ L$. At equilibrium,half a mole of $HI$ is dissociated. The equilibrium constant of the reaction is

Consider the following reaction in a $1 \ L$ closed vessel: $N_2 + 3H_2 \rightleftharpoons 2NH_3$. If all the species $N_2, H_2$ and $NH_3$ are $1 \ mol$ each at the beginning of the reaction and equilibrium is attained when unreacted $N_2$ is $0.7 \ mol$,what is the value of the equilibrium constant?

$2 \ mol$ of $PCl_5$ is heated in a closed vessel of $2 \ L$ capacity. When equilibrium is attained,$PCl_5$ is $40\%$ dissociated. The equilibrium constant $K_c$ for the reaction will be ........... $mol/L$.

For the equilibrium system $A_{(s)} \rightleftharpoons 2B_{(g)} + 3C_{(g)}$,if the concentration of $C$ is doubled at equilibrium,then the concentration of $B$ at equilibrium will become ...