Stability of reactant will be maximum for which value of $K$?

If the equilibrium constant of a reaction is $K_c = 1.6 \times 10^{12}$,then at equilibrium,the system will contain:

Identify which of the following reactions represent homogeneous and heterogeneous equilibria:
$(a)$ $H_{2(g)} + I_{2(g)} \rightleftharpoons 2HI_{(g)}$
$(b)$ $Ca(OH)_{2(s)} \rightleftharpoons Ca^{2+}_{(aq)} + 2OH^{-}_{(aq)}$
$(c)$ $CaCO_{3(s)} \rightleftharpoons CaO_{(s)} + CO_{2(g)}$
$(d)$ $Ag_{2}O_{(s)} + 2H^{+}_{(aq)} \rightleftharpoons H_{2}O_{(l)} + 2Ag^{+}_{(aq)}$
$(e)$ $NH_{3(g)} + H_{2}O_{(l)} \rightleftharpoons N{H_{4}}^{+}_{(aq)} + OH^{-}_{(aq)}$
$(f)$ $CH_{3}COOC_{2}H_{5(l)} + H_{2}O_{(l)} \rightleftharpoons CH_{3}COOH_{(l)} + C_{2}H_{5}OH_{(l)}$

Assertion : The equilibrium constant is fixed and a characteristic for any given chemical reaction at a specified temperature.
Reason : The composition of the final equilibrium mixture at a particular temperature depends upon the starting amount of reactants.

$2 \ HI_{(g)} \rightleftharpoons H_{2(g)} + I_{2(g)}$
The equilibrium constant of the above reaction is $6.4$ at $300 \ K$. If $0.25 \ mol$ each of $H_{2}$ and $I_{2}$ are added to the system,the equilibrium constant will be

For the process $H_2O_{(s)} \rightleftharpoons H_2O_{(l)}$ at $0^{\circ}C$ and $1 \ atm$ pressure,which of the following is true?