Question

How will you distinguish between a plane mirror and convex mirror and concave mirror with touching them?​

Answer 1

If the image is upright of the same size as the object and it does not change
in size by moving the object the mirror is plane.

If the image is upright magnified and it becomes inverted on moving the
object away from the mirror then the mirror is concave.

If the image is upright and diminished and it remains upright on moving
the object away from the mirror then the mirror is convex.