Question

A current of $10.0A$ flows for $2.00h$ through an electrolytic cell containing a molten salt of metal $X$. This results in the decomposition of $0.250mol$ of metal $X$ at the cathode. The oxidation state of $X$ in the molten salt is : $(F=96,500C)$

• A. 1 +
• B. 2 +
• C. 3 +
• D. 4 +

Answer 1

Answer: (C)

$w=\frac{E}{96500}\times It$

$\Rightarrow$ No. of moles $=\frac{It}{96500\times \left(n-factor\right)}$

$\Rightarrow 0.25=\frac{10\times 2\times 60\times 60}{96500\times \text{n-factor}}$

$\Rightarrow$ n - factor $=\frac{720\times 4}{965}=3$

$\therefore$ Oxidation state of molten salt is $+3$