Question

what is the position of object if an object is placed at Infinity for convex lens​

Answer 1

Explanation:

The TEXTBOOK answer is quite nebulous: the image provided by a convex lens of an object at infinity would be located at the lens' FOCUS and it would be a point.

Answer 2

Answer:

Image Formation by Convex Lens

There are six possibilities of position of object in the case of convex lens:

Object at infinity

Object beyond centre of curvature, C

Object at centre of curvature, C

Object between centre of curvature, C and principal focus, F

Object at principal focus, F

Object between principal focus, F and optical centre, O