Question

Explain why a real image can be projected on a screen but virtual image cannot

Answer 1

because  real image is formed by convex lens which is a converging lens
so it could be projected on a screen where as a concave lens is a diverging lens  where rays of light deviate away from each ,so image could not be formed on a screen when it is a virtual image

*concave lens forms virtual images
**convex lens forms real and inverted images