Spherical mirror formula relating an object distance 'u', image distance v' and focal length of mirror f may be applied to a plane mirror when

The correct relation between the radius of curvature R and focal length f of a spherical mirror is

A convex lens has a focal length of 15 cm. At what distance should an object be placed in front of the lens to get a real image of the same size of the object?

The image of an object formed by a plane mirror is

What is the magnification produced by a concave lens of focal length 10 cm, when an image is formed at a distance of 5 cm from the lens?

A point object is placed at the centre of curvature of a spherical concave mirror. Which one among the following would be the correct location of image formed ?