Dimensional Formula of Frequency

Consider the following statements made about the magnification m of an image produced by a convex lens. As the object distance u increases:

(A) From u = 0 to u = f, m increases.

(B) From u = f to u = 2f, m decreases.

(C) From u = 2f to u = ∞, m increases.

Of the above statements:

A simple microscope has a convex lens of focal length 5 cm. If the least distance of distinct vision is 25 cm, the magnification of the microscope in normal adjustment is:

Which of the following phenomenon could not be explained by the wave theory of light?

Of the thermometers given below, the most suitable thermometer to measure the temperature of a drop of liquid is,