How can the neutral body be charged electrically ?

To electrify a neutral body, we need to add or remove one kind of charge.

A body can thus be charged positively by losing some of its electrons. Similarly, a body can be charged negatively by gaining electrons.

The body which removes the electrons its mass decreases slightly and the body which gains the electrons its mass increases.

When we rub a glass rod with silk, some of the electrons from the rod are transferred to the silk cloth. Thus, the rod gets positively charged and the silk gets negatively charged.

No new charge is created in the process of rubbing.