Question

The quantity of charge (in Faraday) required to reduce 96 g Mg from molten solution of MgCl${}_2$ is :

Answer 1

The molar mass of Mg is 24 g/mol.
96 g of Mg corresponds to $\frac{96}{24}=4$moles.
Reduction of 1 mole of Mg requires 2 moles of electrons or 2 faraday of charge.
Hence, the reduction of 4 moles of Mg required 8 faraday of charge.