There are three concentric thin spherical shells A, B and C of radii R, 2R, and 3R. Shells A and C are given charges q and 2q and shell B is earthed. Then which of the given is correct?

As the charge inside shell zero so charge induced at surface is -qas shell B is earthed so potential at any point p on the shell will be zeroassume charge on B is xthen charge on outer surface of A is 2q+x and inner suface is xVp = VA out + VB surface + Vc in = zero 0 = kq2R + k-q+x2R + k2q3R  then x= -4q3q2= x=charge on ouer surface of B=-4q3q3=-x= charge on inner surface of C=4q3q4= 2q+x =charge on outer surface of C=2q+-4q3=2q3