Harsha tells Siddhu that the double convex lens

Harsha tells Siddhu that the double convex lens behaves like a convergent lens. But Siddhu knows that Harsha’s assertion is wrong and corrected Harsha by asking some questions. What are the questions asked by Siddhu?

Siddhu may asked the following questions.
i) What is the shape of the lens. If two convex lenses are attached ?
ii) What happens when a light ray passes through a convex lens ?
iii) What happen when a light ray passes through a double convex lens ?
iv) Is there any convergent point is available, if the light ray passes through a double convex lens ?