What causes an electrical charge to build up on an obiect?​

Static electricity is a buildup of electric charges on objects. Charges build up when negative electrons are transferred from one object to another.

Explanation:

When an object gains electrons, it has a surplus of electrons and is said to have a negative charge. When an object loses electrons, it has a shortage of electrons, it has a shortage of electrons and is said to have a positive charge. The buildup of electric charges is called static electricity.The object that gives up electrons becomes positively charged, and the object that accepts the electrons becomes negatively charged.

conservation of mass

mass before something happens = mass afterwards