Which one of the following statements about the aperture of a convex lens is correct?

Which one of the following statement is not correct?

Which of the following statement is not correct?

Which one of the following statements is not correct for light rays ?

A lens has a power of +2.0 Dioptre. Which one of the following statements about the lens is true ?

Raman effect is due to Sir C. V. Raman. Which of the following statements is correct about 'Raman effect?