Tails of comets are visible due to

(A ): The tails of comets are always oriented in a direction away from Sun (R) : Electromagentic waves exert pressure.

What is a comet ?

Fig. 17.6 shows comets without their tail. Show the tails of the comets at position A, B, and C. In which position will the tail be longest?

When does a comet become visible to us ?

Tailing of mercury is due to formation of _______.