Question

Which of the following can never form a shadow?

Answer 1

Shadows are the dark patch formed by an object. It is formed when the light from a source is obstructed by an object. The objects that do not allow the light to pass through them are called opaque objects. Examples: stone, wood, metals etc.
Here, air is a transparent object. It allows all the light rays to pass through it. Hence, it does not cast shadows. The objects like pen, ball, table are opaque because they do not let the light pass through them. Hence, they form a dark patch on the other side of the object.