Assertion: Be exhibit photoelectric effect.
Reason: Be has least IP in the s-block.

Options

A. If both Assertion & Reason are True & the Reason is a correct explanation of the Assertion
B. If both Assertion & Reason are True but Reason is not a correct explanation of the Assertion
C. If Assertion is True but the Reason is False
D. If both Assertion & Reason are False

Explanation

To solve the question, we need to analyze the assertion and the reason provided:

**Assertion:** Beryllium (Be) exhibits the photoelectric effect.
**Reason:** Beryllium has the least ionization potential (IP) in the s-block.

### Step-by-Step Solution:

1. **Understanding the Photoelectric Effect:**
- The photoelectric effect occurs when light (or radiation) strikes a metal surface and causes the emission of electrons. For a metal to exhibit this effect, it must have a relatively low ionization energy, which is the energy required to remove an electron from the outermost shell.

2. **Ionization Potential in Beryllium:**
- Ionization potential (or ionization energy) is a crucial factor in determining whether a metal can exhibit the photoelectric effect. Generally, the lower the ionization potential, the more readily an electron can be emitted when exposed to light.

3. **Ionization Potential of Beryllium:**
- Beryllium has a relatively high ionization potential compared to other s-block elements. In fact, it has the highest ionization potential among the s-block elements. This is due to its small atomic size and the effective nuclear charge experienced by the outermost electron.

4. **Evaluating the Assertion:**
- Since beryllium has a high ionization potential, it does not readily emit electrons when exposed to light. Therefore, the assertion that beryllium exhibits the photoelectric effect is **incorrect**.

5. **Evaluating the Reason:**
- The reason states that beryllium has the least ionization potential in the s-block, which is also **incorrect**. Beryllium actually has the highest ionization potential among the s-block elements.

6. **Conclusion:**
- Both the assertion and the reason are incorrect. Thus, the correct answer is that both the assertion and the reason are false.

### Final Answer:
Both Assertion and Reason are incorrect (Option D).