Given below are two statements:
Statement I : Out of microwaves , infrared rays and ultraviolet rays, ultraviolet rays are the most effective for the emission of electrons from a metallic surface .
Statement II : Above the threshold frequency, the maximum kinetic energy of photoelectrons is inversely proporyional to the frequency of the incident light.
In the light of above statements, choose the correct answer the options given below

Options

A. Both Statement I and Statement II are true
B. Statement I is false but statement II is true
C. Both Statement I and Statement II false
D. Statement I is true but statement II is false

Answer

To solve the given question, we need to analyze both statements provided:

### Step 1: Analyze Statement I
**Statement I**: "Out of microwaves, infrared rays, and ultraviolet rays, ultraviolet rays are the most effective for the emission of electrons from a metallic surface."

- The emission of electrons from a metallic surface due to incident light is described by the photoelectric effect. According to the photoelectric effect, the energy of the incident light is directly proportional to its frequency (E = hν, where h is Planck's constant and ν is the frequency).
- Ultraviolet rays have a higher frequency compared to microwaves and infrared rays. Therefore, they carry more energy.
- Since ultraviolet rays have a higher frequency, they are indeed more effective in causing the emission of electrons from a metallic surface than microwaves and infrared rays.

**Conclusion**: Statement I is **True**.

### Step 2: Analyze Statement II
**Statement II**: "Above the threshold frequency, the maximum kinetic energy of photoelectrons is inversely proportional to the frequency of the incident light."

- The maximum kinetic energy (K.E.) of the emitted photoelectrons is given by the equation:
\[ K.E. = hν - φ \]
where φ is the work function of the metal.
- From this equation, we can see that the maximum kinetic energy is directly proportional to the frequency of the incident light (hν) and not inversely proportional. As the frequency increases, the kinetic energy of the emitted electrons also increases.

**Conclusion**: Statement II is **False**.

### Final Answer
- Statement I is True.
- Statement II is False.