The standard reduction potentials of $2 \mathrm{H}^{+} / \mathrm{H}_2, \mathrm{Cu}^{2+} / \mathrm{Cu}, \mathrm{Zn}^{2+} / \mathrm{Zn}$ and $\mathrm{NO}_3^{-}, \mathrm{H}^{-} / \mathrm{NO}$ are 0.0 , +0.34 . -0.76 and 0.97 V respectively. Observe the following reactions

I. $\mathrm{Zn}+\mathrm{HCI} \rightarrow$

II. $\mathrm{Cu}+\mathrm{HCl} \rightarrow$

III. $\mathrm{Cu}+\mathrm{HNO}_3 \rightarrow$

Which reactions does not liberate $\mathrm{H}_2(g)$ ?

Aqueous $\mathrm{CuSO}_4$ solution was electrolysed by passing 2 amp of current for 10 min . What is the weight (in g) of copper deposited at cathode ?

$$ \left(\mathrm{Cu}=63 \mathrm{u} ; F=96500 \mathrm{C} \mathrm{~mol}^{-1}\right) $$