The same quantity of electricity was passed through solutions of salts of elements $X$,$Y$,and $Z$ with atomic masses $7$,$27$,and $48$ respectively. The masses of $X$,$Y$,and $Z$ deposited were $2.1 \ g$,$2.7 \ g$,and $7.2 \ g$ respectively. The valencies of $X$,$Y$,and $Z$ respectively are:

How many coulombs are required for the oxidation of $1 \, mol$ of $H_2O_2$ to $O_2$?

In the Hall process,aluminium is produced by the electrolysis of molten $Al_2O_3$. How many seconds would it take to produce enough aluminium by the Hall process to make a case of $24$ cans of aluminium soft-drink,if each can uses $5.0 \ g$ of $Al$,a current of $9650 \ A$ is employed,and the current efficiency of the cell is $90.0 \ \%$?

Cells $A$ and $B$ contain aqueous solutions of ferrous chloride $(FeCl_2)$ and ferric chloride $(FeCl_3)$ respectively. If the same quantity of electricity is passed through both cells, what is the ratio of the mass of iron deposited in cell $A$ to that in cell $B$?

$A$ current $I$ is passed for a time $t$ through a number of voltameters. If $m$ is the mass of a substance deposited on an electrode and $z$ is its electrochemical equivalent,then

For the oxidation of $0.2 \text{ M} \text{ FeSO}_4$ solution,$0.965 \text{ A}$ current is passed through it for $1 \text{ hour}$. The volume of the solution that is oxidised in $\text{mL}$ is: