Question

i.)Between which two points related to a concave mirror should an object be placed to obtain on a screen .
II.)and image twice the size of the object.

Answer 1

HERE IS YOUR ANSWER
THE POINTS ARE
IF WE PUT THE OBJECT BETWEEN THE FOCUS
AND THE POLE
THEN THE IMAGE FORMED WILL be MAGNIFIED

Answer 2

For concave mirror the virtual image is formed when the object is kept in between the pole and the focus.  

Given here the "size of the image" is twice to that of the object.

Hence, it is consider that the magnification is +2.

So, the magnification value is positive and the image formed will be "virtual and erect". Thus, the object should be kept in between the "pole and the focus" in concave mirror."