6.35 g of copper (Atomic mass $=635 \mathrm{u}$ ) is deposited at the cathode from a $\mathrm{Cu}^{2+}$ solution using a certain quantity of electric charge.

The volume of oxygen gas liberated at STP from water electrolysis using the same quantity of electric charge is

How long should water be electrolysed using 50 A current to release enough $\mathrm{H}_2$ gas to completely reduce 8.0 g of CuO ?

$\left(\mathrm{CuO}+\mathrm{H}_2 \longrightarrow \mathrm{Cu}+\mathrm{H}_2 \mathrm{O}\right.$; Atomic mass of $\mathrm{Cu}=635 \mathrm{u}$ )

4.5 g of aluminium (Atomic mass 27 amu ) is deposited at cathode from $\mathrm{Al}^{3+}$ solution by a certain quantity of electric charge. The volume of hydrogen produced at STP from $\mathrm{H}^{+}$ions in the solution by the same quantity of electric charge will be

How long should water be electrolysed by passing through 100 amperes current so that oxygen released can completely burn 27.66 g of diborane? (Weight of $B=10.8 \mathrm{u}$ )