By which instrument can the charge on an object be detected?

Assertion $(A)$: Electromagnetic force is enormously strong as compared to gravitational force. Yet,gravity dominates in large-scale phenomena (e.g.,formation of galaxies).
Reason $(R)$: Existence of positive and negative charges makes matter mostly electrically neutral.
Which of the following is true?

$A$ solid of mass $1 \ kg$ has $6 \times 10^{24}$ atoms. If one electron is removed from every one atom of $0.005 \%$ of the atoms,then the charge gained by the solid is

$A$ conductor has $14.4 \times 10^{-19} \ C$ of positive charge. The conductor has (Charge on an electron $= 1.6 \times 10^{-19} \ C$):

What is the total charge of the electrons in a neutral atom?

Which scientist represented the types of charges?