Differentiate lens without touching

Q. :- Suppose two different types of lenses i.e. convex and concave lenses forming virtual image. By looking image how can you differentiate between them without touching it?

Ans – As we know that convex can form both real and virtual image. Real image formed by convex lens may be magnified, equal in size or, diminished but virtual image is always magnified.

Whaereas concave lens always forms virtual image and diminished.

So, by looking virtual image convex lens can be recognished if it forms magnified and concave forms diminished. So, it can be differentiated without touching the lens.