$A$ body can be negatively charged by which of the following methods?

$A$ $1$ paisa coin is made up of an $Al-Mg$ alloy and weighs $0.75\, g$. It has a square shape and its diagonal measures $17\, mm$. It is electrically neutral and contains equal amounts of positive and negative charges. Calculate the total amount of positive or negative charge in the coin.

If a body is charged by rubbing it,its weight:

When a glass rod is rubbed with a silk cloth,charges appear on both. $A$ similar phenomenon is observed with many other pairs of bodies. Explain how this observation is consistent with the law of conservation of charge.

Mention the types of methods of charging a body.

Two identical spherical conductors $B$ and $C$ have equal radii and carry equal charges. They repel each other with a force $F$ when placed at a certain distance apart. $A$ third identical spherical conductor $A$,which is uncharged,is brought in contact with $B$ and then removed. It is then brought in contact with $C$ and removed. What is the new force of repulsion between $B$ and $C$?