If the image formed by a convex lens is of the same size as that of the object, what is the position of the image with respect to the lens?

Give the usual name for the following :

A point inside a lens through which the light passes undeviated.

A 1 cm high object is placed at a distance of 2f from a convex lens. What is the height of the image formed?

If an object is placed at the focus of a convex lens, where is the image formed?

Where should an object be placed in order to use a convex lens as a magnifying glass?