Which of the following always form a virtual image?

$A$ dice is placed with one of its edges parallel to the principal axis between the principal focus $(F)$ and the centre of curvature $(C)$ of a concave mirror. Then the final image has the shape of

Where is the image formed when an object is placed at a distance of $2f$ in front of a convex mirror?

What will be the focal length of a lens whose power is given as $+2.0 \ D$?

Rays from the Sun converge at a point $15 \, cm$ in front of a concave mirror. Where should an object be placed so that the size of its image is equal to the size of the object?

The nature,size,and position of the image of an object produced by a lens or mirror are as shown below. Identify the lens/mirror $(X)$ used in each case and draw the corresponding complete ray diagram.