Question

What causes the charging of two objects when they are rubbed together?

Answer 1

CAUSE OF CHARGING OF TWO OBJECTS WHEN RUBBED:
Both objects before rubbing are neutral.
On Rubbing transfer of electrons from one object to other object takes place.
The body from which electrons are transferred gets DEFICIENT in ELECTRONS and becomes POSITIVELY charged.
The body to which electrons are transferred has EXCESS ELECTRONS and becomes NEGATIVELY charged.