Where should an object be placed from a converging lens of focal length 10 c, so as to obtain a virtual image of magnification 2 ?

Where should an object be placed from a converging lens of focal length 20 cm, so as to obtain a real image of magnification 2?

Where should an object be placed from a converging lens of focal length 20 cm, so as to obtain a real image of magnification 2?

Where should an object placed from a conveging lens of focal length 20 cm,so as to obtain a real image of magnification 2?

An object is placed 80 cm from converging lens of focal length 25 cm. What is the nature of image?

Two lenses of power +10 D and - 5 D are placed in contact. Where should an object be held from the lens, so as to obtain a virtual image of magnification 2 ?

Two lenses of power +10 D and - 5 D are placed in contact. Where should an object be held from the lens, so as to obtain a virtual image of magnification 2 ?

Calculate the distance at which an object should be placed in front of a convex lens of focal length 10 cm to obtain a virtual image of double its size.