Let A and B are two identical objects of same mass initially are charged electrostatically by rubbing against each other. Let A has got a positive charge and B has got a negative charge, then match column I and column II

B is negatively charged, so mass of ,B increases due to gain of electrons. As A loses electrons its mass decreases. Work function (minimum energy required by an e− to comes onto a surface) of A is less, so it readily loses e−