Which of the following salts will give highest $\mathrm{pH}$ in water? 

The percentage of pyridine (${\mathrm{C}}_5{\mathrm{H}}_5\mathrm{N}$) that forms a pyridinium ion (${\mathrm{C}}_5{\mathrm{H}}_5{\mathrm{N}}^{+}\mathrm{H}$) in a $0.10 \mathrm{M}$ aqueous pyridine solution is, (${\mathrm{K}}_{\mathrm{b}} \mathrm{for} {\mathrm{C}}_5{\mathrm{H}}_5\mathrm{N}=1.7\times {10}^{-9}$).

Following solutions were prepared by mixing different volumes of $\mathrm{NaOH} \text{and} \mathrm{HCl}$of different concentrations ?

a. $60\mathrm{mL}\frac{\mathrm{M}}{10}\mathrm{HCl}+40\mathrm{mL}\frac{\mathrm{M}}{10}\mathrm{NaOH}$
b. $55\mathrm{mL}\frac{\mathrm{M}}{10}\mathrm{HCl}+45\mathrm{mL}\frac{\mathrm{M}}{10}\mathrm{NaOH}$

c. $75\mathrm{mL}\frac{\mathrm{M}}{5}\mathrm{HCl}+25\mathrm{mL}\frac{\mathrm{M}}{5}\mathrm{NaOH}$
d. $100\mathrm{mL}\frac{\mathrm{M}}{10}\mathrm{HCl}+100\mathrm{mL}\frac{\mathrm{M}}{10}\mathrm{NaOH}$

Consider the reaction equilibrium

$2{\mathrm{SO}}_2\left(\mathrm{g}\right)+{\mathrm{O}}_2\left(\mathrm{g}\right)\rightleftharpoons 2{\mathrm{SO}}_3\left(\mathrm{g}\right); \mathrm{\Delta H}°=-198 \mathrm{kJ}$

On the basis of Le Chatelier's principle, the condition favorable for the forward reaction is