Question

If '$\mathrm{a}$' $\mathrm{g}$ of a divalent metal gets deposited at the cathode by passing $1\mathrm{A}$of current for $30\min ,$ calculate its atomic weight.

• A. $214.4\mathrm{a}$
• B. $180\mathrm{a}$
• C. $107.2\mathrm{a}$
• D. $53.6\mathrm{a}$

Answer 1

The correct option is C

$107.2\mathrm{a}$

Explanation for the correct option:

The metal given in the question is a divalent, so it is +2 state.

The mass of metal deposited on the cathode is $\text{'}\mathrm{a}\text{'}\mathrm{g}$.

The amount of Current used is 1 A.

Time taken for the electrolysis to occur is $30\min =30\times 60=1800\sec$

The atomic weight of the metal can be calculated as:

$\mathrm{M}=\frac{\mathrm{W}\times \mathrm{F}\times \mathrm{z}}{\mathrm{C}\times \mathrm{t}}$

Where M is the atomic mass of the metal, W is the weight is the substance deposited, F is 1 Faraday = 96500, z is the Valency of the metal, C is the current passed and t is the time taken.

Putting all the values, we get:

$\mathrm{M}=\frac{\mathrm{a}\times 96500\times 2}{1\times 1800}=107.2\mathrm{a}$

So, the Atomic mass of the metal is 107.2 a.

Therefore, the correct option is (C).