Question

Three Faradays of electricity was passed through an aqueous solution of magnesium bromide. The weight of magnesium metal deposited at the cathode in grams is:

• A. 56
• B. 84
• C. 36
• D. 168

Answer 1

The correct option is C 36

$MgB{r}_2$ has $M{g}^{2+}$ ions.

$M{g}^{2+}$ + 2e => Mg

2 moles of electron deposits 1 mole of Mg.

1 mole of electron = 1 Faraday

3 moles of the electron will yield = 3/2 moles of Mg.

1 mole of Mg= 24 gm.

therefore 3/2 moles of Mg= 36 gm.

Option C is correct.