Electrolysis of a solution of ${\mathrm{MnSO}}_4$ in aqueous sulphuric acid is a method for the preparation of ${\mathrm{MnO}}_2$ as per the reaction ${\mathrm{Mn}}^{2+} \left(\mathrm{aq}\right)+2{\mathrm{H}}_2\mathrm{O}⟶{\mathrm{MnO}}_2 \left(\mathrm{s}\right)+2{\mathrm{H}}^{+} \left(\mathrm{aq}\right)+{\mathrm{H}}_2 \left(\mathrm{g}\right)$

Passing a current of $27 \mathrm{A}$ for $24 \mathrm{hours}$ gives one $\mathrm{kg}$ of ${\mathrm{MnO}}_2$. What is the value of current efficiency? Write the reactions taking place at the cathode and at the anode.

How many equivalents are there in $98 \mathrm{g}$ of ${\mathrm{H}}_2{\mathrm{SO}}_4$ in the following reaction?

$8{\mathrm{H}}^{+}+{\mathrm{H}}_2{\mathrm{SO}}_4+4\mathrm{Zn}⟶{\mathrm{H}}_2\mathrm{S}+4{\mathrm{Zn}}^{2+}+4{\mathrm{H}}_2\mathrm{O}$

Also, find out the equivalent weight of ${\mathrm{H}}_2{\mathrm{SO}}_4$ in this reaction.

What is the molarity of $4 \mathrm{N} {\mathrm{H}}_2{\mathrm{SO}}_4$ in the following reaction?

$8{\mathrm{H}}^{+}+{\mathrm{H}}_2{\mathrm{SO}}_4+8{\mathrm{e}}^{-}⟶{\mathrm{H}}_2\mathrm{S}+4{\mathrm{H}}_2$

An aqueous solution contains $10 \%$ ammonia by mass and has a density of $0.99 \mathrm{g}/\mathrm{cc}$.

Calculate the hydroxyl and hydrogen-ion concentration in this solution.
${\mathrm{K}}_{\mathrm{a}}\left({\mathrm{NH}}_4^{+}\right)=5\times {10}^{-10} \mathrm{M}$

Calculate the equilibrium constant for the reaction

${\mathrm{Fe}}^{2+}+{\mathrm{Ce}}^{4+}\rightleftharpoons {\mathrm{Fe}}^{3+}+{\mathrm{Ce}}^{3+}$

Given, ${\mathrm{E}}_{{\mathrm{Ce}}^{4+}/{\mathrm{Ce}}^{3+}}^0=1.44 \mathrm{V}; {\mathrm{E}}_{{\mathrm{Fe}}^{3+}/{\mathrm{Fe}}^{2+}}^0=0.68 \mathrm{V}$.

If the answer is of type $\mathrm{y}\times {10}^{12}$, report the value of $\mathrm{y}$ correct up to one place of decimal.