(a) Find out the position of the image of an object situated at A in the plane mirror (Fig. 16.21).

(b) Can Paheli at B see this image?

(c) Can Boojho at C see this image?

(d) When Paheli moves from B to C, where does the image of A move?

(a) Image of the object placed at A is formed behind the mirror. The image is shown as A'.

Now, it is the characteristic of the image formation of plane mirror that  "the distance of the image from the mirror is equal to the distance of the object from the mirror".

∴ The distance of A from the mirror is equal to the distance of A' from the mirror.

(b) Yes, Paheli at B position will be able to see this image.  This is because of the reflected rays from the mirror will reach Paheli's eyes.   

(c) Yes. Boojho at C can see this image. Because the position of Boojho is just ahead of Paheli, and not far away. 

(d) Image of the object at A will not move. It will remain at the same position when Paheli moves from B to C.