$\mathrm{Assertion} \left(\mathrm{A}\right) :$ Buffer solution are composed of strong acids and strong bases.

$\mathrm{Reason} \left(\mathrm{R}\right) :$ It maintains the $\mathrm{pH}$ to constant value of $7.4$. 

$\mathrm{Assertion} \left(\mathrm{A}\right):$ The ionization of hydrogen sulphide in water is low in the presence of $\mathrm{HCl}$.

$\mathrm{Reason} \left(\mathrm{R}\right):$ ${\mathrm{H}}_2\mathrm{S}$ is a weak acid.

$\mathrm{Assertion}:$ ${\mathrm{Na}}_2{\mathrm{SO}}_3$ solution gives basic solution in litmus solution.

$\mathrm{Reason}:$ It reacts with water and form ${\mathrm{H}}_2{\mathrm{SO}}_3$. 

Using the Gibbs energy change, $\mathrm{\Delta G}°=+633 \mathrm{kJ},$ for the following reaction,

${\mathrm{Ag}}_2{\mathrm{CO}}_3( \mathrm{s})\underset{}{\overset{}{\rightleftarrows }}2{\mathrm{Ag}}^{+}\left(\mathrm{aq}\right)+C{O}_3^{2-}\left(\mathrm{aq}\right)$,  the ${\mathrm{K}}_{\mathrm{sp}}$ of ${\mathrm{Ag}}_2{\mathrm{CO}}_3\left(\mathrm{s}\right)$ in Water at $25°\mathrm{C}$ is $\left(\mathrm{R}=8314{\mathrm{JK}}^{-1}{\mathrm{moI}}^{-1}\right):$