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.

Which of the following is the correct general form of Snell's law?

What is the focal length of a convex lens having power $+5.0 \,D$?

Magnification produced by a rear-view mirror fitted in vehicles $....$

What will be the angle of refraction for a light ray incident normally at the surface (in $^{\circ}$)?

$A$ student focused the image of a candle flame on a white screen using a convex lens. He noted down the positions of the candle,screen,and lens as follows:
Position of candle $= 12.0 \, cm$
Position of convex lens $= 50.0 \, cm$
Position of the screen $= 88.0 \, cm$
$(i)$ What is the focal length of the convex lens?
$(ii)$ Where will the image be formed if he shifts the candle towards the lens to a position of $31.0 \, cm$?