Molten $MgCl X_{2}$ is electrolysed and $2.40 g$ of magnesium is obtained at the cathode. The volume of chlorine gas liberated at the anode, measured at STP, is (Mg = 24, molar volume at STP $= 22.4 L$ )

Answer: B

Cathode:

Mg X^{2 +} + 2 e X^{-} Mg

; anode:

2 Cl X^{-} Cl X_{2} + 2 e X^{-}

. The same two electrons give one Mg and one

Cl X_{2}

, so moles of

Cl X_{2}

= moles of Mg

= 2.40/24 = 0.100 mol

. Volume at STP

= 0.100 \times 22.4 = 2.24 L