Three particles each having a mass 100 gm are placed on the verticles of an equilateral triangle of side 20 cm. The work done in increasing the side of their triangle to 40 cm is $(G= 6.67 \times 10^{-11}\;Nm^2/kg^2)$

Question

$$(a)\;5.0 \times 10^{-12}\;J \quad (b)\;2.25 \times 10^{-10}\;J \quad (c)\;4.0 \times 10^{-11}\;J \quad (d)\;6.0 \times 10^{-15}\;J$$