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

Can we neglect the quantization of charge? If yes,then mention the situation.

What type of charges are obtained on silk cloth and glass rod when they are rubbed against each other?

How many electrons are there in $1 \ C$ of charge?

We have three identical metallic spheres $A, B$ and $C$. $A$ is given a charge $Q$,and $B$ and $C$ are uncharged. The following processes of touching of two spheres are carried out in succession. Each process is carried out with sufficient time.
$(i)$ $A$ and $B$
$(ii)$ $B$ and $C$
$(iii)$ $C$ and $A$
$(iv)$ $A$ and $B$
$(v)$ $B$ and $C$
The final charges on the spheres are

Which instrument is used to detect the charge on a body? Explain it with a diagram.