Question

Three faraday of electricity is passed through three electrolytic cells connected in series containing $Ag ^{+}, Ca ^{2+}$ and $Al ^{3+}$ ions respectively. The molar ratio in which the three metal ions are liberated at the electrodes is

• A. $1: 2: 3$
• B. $3: 2: 1$
• C. $6: 3: 2$
• D. $3: 4: 2$

Answer 1

Answer: (C)

for $1$ mole electrons $=1$ faraday $\longrightarrow 1$ mole of $Ag ^{+}$
for $1$ mole electrons $=1$ faraday $\longrightarrow \frac{1}{2}$ mole of $Ca ^{2+}$
for $1$ mole electrons $=1$ faraday $\longrightarrow \frac{1}{3}$ mole of $Al ^{3+}$
So for $3$ faraday $\rightarrow 1 \times 3, \frac{1}{2} \times 3, \frac{1}{3} \times 3$
$3: \frac{3}{2}: 1 $ or $ 6: 3: 2 $