[આપેલ : $1\,F =96500\,C\,mol ^{-1},$ $Fe$નું પરમાણ્વીય દળ $= 56\,g\,mol ^{-1}$ ]
$3 F \longrightarrow 1$ mole $Fe$ is deposited
For $56\, g \longrightarrow 3 \times 96500$ (required charge)
For $1 \,g \longrightarrow \frac{3 \times 96500}{56}$ (required charge)
For $0.3482\, g \longrightarrow \frac{3 \times 96500}{56} \times 0.3482$
$Q =i\,t$
$1800.06=1.5 \,t$
$t =20\, min$