The negative $Zn$ pole of a Daniel cell,sending a constant current through a circuit,decreases in mass by $0.13 \ g$ in $30$ minutes. If the electrochemical equivalent of $Zn$ and $Cu$ are $32.5$ and $31.5$ respectively,the increase in the mass of the positive $Cu$ pole in this time is .............. $g$.

The quantity of electricity required to liberate $112 \, cm^3$ of hydrogen at $STP$ from acidified water is

Three voltameters containing aqueous solutions of $H_2SO_4$,$CuSO_4$,and $AgNO_3$ are connected in series as shown. $A$ current was passed for $10 \ hours$. $10.8 \ g$ of $Ag$ was deposited at the cathode in the $(III)$ electrolytic cell during electrolysis. If the current efficiency is $50\%$,what is the magnitude of the current in amperes?

During the electrolysis of acidified water, $16 \text{ g}$ of $O_2$ gas is formed at the anode. The volume of $H_2$ gas liberated at the cathode under $STP$ conditions is: (in $text{ L}$)

$A$ constant current $(0.5 \, A)$ is passed for $1 \, hour$ through $(i)$ aqueous $AgNO_3$,$(ii)$ aqueous $CuSO_4$ and $(iii)$ molten $AlF_3$,separately. The ratio of the mass of the metals deposited on the cathode is $[M_{Ag}, M_{Cu}, M_{Al}$ are molar masses of the respective metals.]

Salts of $A$ (atomic weight $8$),$B$ (atomic weight $18$) and $C$ (atomic weight $50$) were electrolysed under identical conditions using the same quantity of electricity. It was found that $2.4 \ g$ of $A$ was deposited,the weight of $B$ and $C$ deposited are $1.8 \ g$ and $7.5 \ g$ respectively. The valences of $A$,$B$ and $C$ are,respectively,