Question

A copper voltameter, a silver voltameter and a water voltameter are connected in series and current is passed through them for some time. The ratio of the number of moles of copper, silver and hydrogen formed at the cathode is:

• A. $2:1:1$
• B. $1:1:1$
• C. $1:2:1$
• D. $1:2:2$

Answer 1

Answer: (C)

$1:2:1$

$C{u}^{2+}+2e^{-}\to Cu$

$2H^{+}+2e^{-}\to H_2$

$A{g}^{+}+e^{-}\to Ag$

The charge is same as the current is same.

$\therefore No.ofmoles\propto \frac{1}{Numberofelectronsrequired}$
$Cu:Ag:H_2=\frac{1}{2}:1:\frac{1}{2}=1:2:1$

Hence, option C is correct.