A vertical cylinder of cross-sectional area $0.1m^2$ closed at both ends is fitted with a frictionless piston of mass M dividing the cylinder into two parts. Each part contains one mole of an ideal gas in equilibrium at 300 K. The volume of the upper part is $0.1m^3$ and that of the lower part is $0.05m^3$ .What force must be applied to the piston so that the volume of the two parts remain unchanged when the temperature is increased to 500 K? Express force as $\left(x\times 100\right)R$ newton and find x? Here R is gas constant in SI unit.