In a copper voltameter experiment,current is decreased to one-fourth of the initial value but it is passed for four times the earlier duration. The amount of copper deposited will be:

$A$ metal surface of $100 \, cm^2$ area has to be coated with a nickel layer of thickness $0.001 \, mm$. $A$ current of $2 \, A$ was passed through a solution of $Ni(NO_3)_2$ for '$x$' seconds to coat the desired layer. The value of $x$ is $.........$. (Nearest integer)
($\rho_{Ni}$ (density of Nickel) is $10 \, g \cdot cm^{-3}$,Molar mass of Nickel is $60 \, g \cdot mol^{-1}$,$F = 96500 \, C \cdot mol^{-1}$)

What current strength is required to deposit $36 \ g$ of $Ag$ in $7 \ minute$ from $AgNO_3$ solution by electrolysis (in $A$)? (Atomic mass $Ag = 108$)

In the electrolysis of an aqueous $NiI_2$ solution using $Ni$ electrodes,what happens to the mass of the cathode upon passing $1$ equivalent of charge? (Given: atomic mass of $Ni = 59$)

$A$ dilute solution of sulphuric acid is electrolysed using a current of $0.10 \ A$ for $2 \ hours$ to produce hydrogen and oxygen gas. The total volume of gases produced at $STP$ is $...... \ cm^3$. (Nearest integer) $[$ Given : Faraday constant $F = 96500 \ C \ mol^{-1}$ at $STP$,molar volume of an ideal gas is $22.7 \ L \ mol^{-1} ]$

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: