Write unit and value of fundamental electric charge.

What are called conductors and non-conductors ? In which free electrons are more ? Conductor or non-conductor.

Which of the following processes involves the principle of electrostatic induction?

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