Conductivity of 1 M KCl  solution is 1.29 S m^-1 and its resistance is 100 ohms. Conductivity of 0.2 M KCl solution whose resistance is 520 ohms will be

The cell constant is given by the equation: 
Cell constant,
 $\begin{array}{l}{\mathrm{G}}^{\ast }=\text{ conductivity }\times \text{ resistance }\\ =1.29\mathrm{S}/\mathrm{m}\times 100\mathrm{\Omega }\\ =129{\mathrm{m}}^{-1}=1.29{\mathrm{cm}}^{-1}\end{array}$
Conductivity of 0.2 mol L^-1 KCI solution
        $\begin{array}{l}\text{ cell constant/ resistance }\\ =\frac{{\mathrm{G}}^{\ast }}{\mathrm{R}}=\frac{129{\mathrm{m}}^{-1}}{520\mathrm{\Omega }}=0.248{\mathrm{Sm}}^{-1}\end{array}$