Explanation

(d)
$w\ = 60\ g$
$i\ = \ 5A$
Equivalent weight of $Ca\ = \ \frac{atomic\ weight}{valency}\$
$= \ \frac{40}{2} = 20$
According to first law of Faraday electrolysis
$w\ = \ Zit\ = \ \frac{equivalent\ weight}{96500}\ \times i\ \times t$
$\therefore\ 60\ = \ \frac{20}{96500}\ \times 5\ \times t$
$t\ = \ \frac{96500\ \times 60}{20\ \times 5}\ s$
$= \ \frac{96500\ \times 60}{20\ \times 5\ \times 60\ \times 60}h$
= 16.08 h