What is the charge on an electron?

Which of the following is not true about electric charge?

What is a point charge?

Rubbing a plastic rod with wool gives the plastic rod a negative charge of $8 \times 10^{-7} \ C$. How many electrons have been transferred,and from where to whom?

How much positive and negative charge is there in a cup of water $(250 \; g)$?

$A$ solid sphere of mass $1 \ gm$ contains $5 \times 10^{21}$ atoms. If one electron is removed from every $0.01\%$ of the atoms,what is the charge acquired by the sphere in $C$?