The approximate time duration in hours to electroplate 20 g of calcium from molten calcium chloride using a current of 4 A is (Atomic mass of $\mathrm{Ca}=40$ )

The pH of 0.5 L of 1.0 M NaCl solution after .electrolysis for 965 s using 5.0 A current is,

Calculate the molarity of a solution containing 5 g of NaOH dissolved in the product of $ \mathrm{H}_{2}-\mathrm{O}_{2} $ fuel cell operated at 1 A current for 595.1 hours. (Assume $ \mathrm{F}=96500 \mathrm{C} / \mathrm{mol} $ of electron and molecular weight of NaOH as $ 40 \mathrm{~g} \mathrm{~mol}^{-1} $ ).

The equilibrium constant of the reaction

$$A(s)+2 B^{+}(a q) \rightleftharpoons A^{2+}(a q)+2 B(s)$$

$$E_{\text {cell }}^{\circ}=0.0295 \mathrm{~V} \text { is } \quad\left[\frac{2.303 R T}{F}=0.059\right]$$