Please solve... what will be the potential on the small sphere when.the switch S is opened...? How do we do it...??! Does the small spehere get Q/3 charge on itself..?? The answer says that the potential on small sphere is same as that of the large sphere...

Two thin conducting shells of radii R and 3 R are shown in the figure. The outer shell carries a charge + Q and the inner shell is neutral. The inner shell is earthed with the help of a switch S. Based on the information, which of the following statements are correct?