Answer
(a) The mass of the sphere is smaller.
(b) The rod has a positive charge.
Work Step by Step
(a) Initially the sphere is uncharged. If the metal sphere becomes positively charged, some electrons must have left the sphere and moved to the rod. Since the sphere lost some electrons, the mass of the sphere is smaller.
(b) Since touching the uncharged sphere with the rod made some electrons move from the sphere to the rod, the rod must have a positive charge.
