Assuming no change in volume, the time required to obtain solution of pH = 12 by electrolysis of 50 mL 0.1 M NaCl (using current of 0.5 amp) will be

Step-by-step solution

[ H + ] = 1 0 - 12 M So [ O H - ] = 1 0 - 2 M Number of moles of NaOH in 50 mL solution = M V 1000 = 1 0 - 2 × 50 1000 = 5 × 1 0 - 4 Mass of NaOH in the solution = 5 × 1 0 - 4 × 40 = 2 × 1 0 - 2 g W = I t E 96500 2 × 1 0 - 2 = 0.5 × t × 40 96500 t = 96.5 sec.