Assertion: The amphoteric behaviour of water is explained by Lewis acid base theory

Reason: water acts as acid with ${\mathrm{NH}}_3$ and base with ${\mathrm{H}}_2\mathrm{S}$

$50 \mathrm{mL}$ of $0.1 \mathrm{M} {\mathrm{CH}}_3\mathrm{COOH}$ is being titrated against $0.1 \mathrm{M} \mathrm{NaOH}$. When $25 \mathrm{mL}$ of $\mathrm{NaOH}$ has been added, the $\mathrm{pH}$ of the solution will be____$\times {10}^{-2}$. (Nearest integer)

(Given : ${\mathrm{pK}}_{\mathrm{a}}\left({\mathrm{CH}}_3\mathrm{COOH}\right)=4.76$)

$\log 2=0.30$

$\log 3=0.48$

$\log 5=0.69$

$\log 7=0.84$

$\log 11=1.04$

$2{\mathrm{NOCl}}_{\left(\mathrm{g}\right)}\rightleftharpoons 2{\mathrm{NO}}_{\left(\mathrm{g}\right)}+{{\mathrm{Cl}}_2}_{\left(\mathrm{g}\right)}$

In an experiment, $2.0$ moles of $\mathrm{NOCl}$ was placed in a one-litre flask and the concentration of $\mathrm{NO}$ after equilibrium established, was found to be $0.4 \mathrm{mol}/\mathrm{L}$. The equilibrium constant ${\mathrm{K}}_{\mathrm{c}}$ at $30 °\mathrm{C}$ is a$\times {10}^{-4}$. Calculate the value of $\mathrm{a}$ and give answer to the nearest integer value

${\mathrm{Ka}}_1,{\mathrm{Ka}}_2$ and ${\mathrm{Ka}}_3$ are the respective ionization constants for the following reactions $\left(\mathrm{a}\right),\left(\mathrm{b}\right)$ and $\left(\mathrm{c}\right)$.

(a) ${\mathrm{H}}_2{\mathrm{C}}_2{\mathrm{O}}_4\rightleftharpoons {\mathrm{H}}^{+}+{\mathrm{HC}}_2{\mathrm{O}}_4^{-}$

(b) ${\mathrm{HC}}_2{\mathrm{O}}_4^{-}\rightleftharpoons {\mathrm{H}}^{+}+{\mathrm{HC}}_2{\mathrm{O}}_4^{2-}$

(c) ${\mathrm{H}}_2{\mathrm{C}}_2{\mathrm{O}}_4\rightleftharpoons 2{\mathrm{H}}^{+}+{\mathrm{C}}_2{\mathrm{O}}_4^{2-}$

The relationship between ${\mathrm{K}}_{{\mathrm{a}}_1},{ \mathrm{K}}_{{\mathrm{a}}_2}$ and ${\mathrm{K}}_{{\mathrm{a}}_3}$ is given as