$A$ convex mirror is used to form the image of a real object. Then tick the wrong statement.

$(a)$ Two lenses have powers of $(i) +2 \text{ D}$ and $(ii) -4 \text{ D}$. What is the nature and focal length of each lens?
$(b)$ An object is kept at a distance of $100 \text{ cm}$ from a lens of power $-4 \text{ D}$. Calculate the image distance.

The image formed by a lens is always erect and diminished. What is the nature of the lens?

The mirror outside the driver's side of a vehicle is usually a convex mirror. Printed on such a mirror is usually the warning "Vehicles in this mirror are closer than they appear". What is the reason for this warning?

What happens when a light ray incident normally on the surface of a glass slab enters from air into the glass?

Name the type of lens that can be used to obtain:
$(i)$ $A$ magnified and virtual image.
$(ii)$ $A$ diminished and virtual image of the object.