Question

the minimum distance between an object and its real image formed by concave mirror of focal length is​

Answer 1

The minimum distance between an object and its real image in the case of a concave mirror is Zero. When the object is at the 2F distance i.e. the center of curvature, then the image is real and formed inverted at the same distance.

Answer 2

HI HERE IS YOUR ANSWER DEAR.

$\huge0$

because when the object is placed at C the image is formed at C which is real and inverted and the distance between the object and distance is always 0