Resistance of a conductivity cell filled with a solution of an electrolyte of concentration 0.1 M is $100 \Omega$. The conductivity of this solution is $1.29 \mathrm{~S} \mathrm{~m}^{-1}$. Resistance of the same cell when filled with 0.2 M of the same solution is 520 Q. The molar conductivity of 0.02 M solution of the electrolyte will be
[2006]
(a) $124 \times 10^{-4} \mathrm{~S} \mathrm{~m}^2 \mathrm{~mol}^{-1}$
(b) $1240 \times 10^{-4} \mathrm{~S} \mathrm{~m}^2 \mathrm{~mol}^{-4}$
(c) $1.24 \times 10^{-4} \mathrm{~S} \mathrm{~m}^2 \mathrm{~mol}^{-1}$
(d) $12.4 \times 10^{-4} 5 \mathrm{mr}^2 \mathrm{~mol}^{-1}$