A clock 'S' is based on oscillations of a spring and a clock P is based on pendulum motion. Both clocks run at the same rate on earth. On a planet having the same density as earth but twice the radius

Acceleration of gravity on the surface of a planet is given byg=43GπRρ        where ρ= Density   and R = RadiusAs    and Rp = 2Rewe can write gp = 2gesince   , we can conclude that time period of p on the surface of planet will decrease.Also for clock s,  Ts on the planet = Ts on earth. So on the surface of planet P will run faster than S.