When a current of $0.5 \ A$ is passed for $2 \ hours$ through a molten metal salt,$3.88 \ g$ of the metal was deposited. If the atomic mass of the metal is $208 \ units$,the oxidation state of the metal in the salt is:

Calculate the amount of electricity required to convert $1.1 \ mol$ of $Cr_2O_7^{2-}$ to $Cr^{3+}$ in acidic medium.

When $1 \ F$ of electricity is passed through acidulated water,the volume of $O_2$ evolved at $STP$ is ............. $dm^{3}$.

When a copper voltameter is connected with a battery of $e.m.f.$ $12 \ V$,$2 \ g$ of copper is deposited in $30 \ minutes$. If the same voltameter is connected across a $6 \ V$ battery,then the mass of copper deposited in $45 \ minutes$ would be ............. $g$.

$A$ current of $2.0 \ A$ is passed for $5 \ hours$ through a molten metal salt,which deposits $22.2 \ g$ of metal (At. wt. $= 177$). The oxidation state of the metal in the metal salt is:

Copper sulphate solution is electrolysed between two platinum electrodes. $A$ current is passed until $1.6 \ g$ of oxygen is liberated at the anode. The amount of copper deposited at the cathode during the same period is .............. $g$ [At. mass of $Cu = 63.6$]