Question

One litre solution of MgCl₂ is electrolyzed completely by passing a current of 1A for 16 min 5 sec. The original concentration of MgCl₂ solution was (Atomic mass of Mg = 24)

• A. 0.5 × 10⁻³ M
• B. 1.0 × 10⁻² M
• C. 5 × 10⁻³ M
• D. 5 × 10⁻² M

Answer 1

Answer: (C)

$m=\frac{EIZ}{96500}=\frac{12\times1\times965}{96500}=12\times10^{-2} g$
$Molarity,\,M=\frac{w_{2}}{M_{2}}\times\frac{1000}{V_{sol}}=\frac{12\times10^{-2}}{24}\times\frac{1000}{1000}=0.5\times10^{-2}=5\times10^{-3} M$