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

What is called quantization of electric charge? Write the $SI$ unit of electric charge.

Faraday's law of electrolysis indirectly shows:

Select the correct alternative.

There are two metallic spheres of same radii but one is solid and the other is hollow, then

When a piece of polythene is rubbed with wool,a negative charge of $4 \times 10^{-7} \ C$ is developed on the polythene. The number of electrons transferred from wool to polythene is $\left[e = 1.6 \times 10^{-19} \ C\right]$.