Dear student,
The image of the pin will appear at the distance of 4.9 cm from the plane mirror. This is because of the property of a plane mirror which states that the distance from the object to the plane mirror will be equal to the distance of the image from the plane mirror and also will be of the same size as that of the object. Thus, raj will find the image of the pin at the distance of 4.9 cm from the plane mirror same as the distance of the object from the plane mirror at which it is placed.
Regards