Sure check for presence of electric charge is

A body has $-\, 80$ $micro\, coulomb$ of charge. Number of additional electrons in it will be

Mention the $SI$ unit and value of fundamental charge. Write its smaller units.

A conductor has $14.4 \times {10^{ – 19}}coulombs$ positive charge. The conductor has(Charge on electron $ = 1.6 \times {10^{ – 19}}coulombs$)

Five balls numbered $1$ to $5$ are suspended using separate threads. Pairs $(1, 2)$, $(2, 4)$ and $(4, 1)$ show electrostatic attraction, while pair $(2, 3)$ and $(4, 5)$ show repulsion. Therefore ball $1$ must be