In the following questions, a statement of assertion (A) is followed by a statement of reason (R )
A : Bond order of `H_(2)^(+)` is 0.5
R : Electrons are removed from the antibonding molecular orbital from `H_(2)` .

Options

A. If both Assertion & Reason are true and the reason is the correct explanation of the assertion, then mark (1)
B. If both Assertion & Reason are true but the reason is not the correct explanation of the assertion, then mark (2)
C. If Assertion is true statement but Reason is false, then mark (3)
D. If both Assertion and Reason are false statements , then mark (4).

Answer

To solve the problem, we need to analyze both the assertion (A) and the reason (R) given in the question.

### Step-by-Step Solution:

1. **Understanding the Assertion (A)**:
- The assertion states that the bond order of \( H_2^+ \) is 0.5.
- To determine the bond order, we use the formula:
\[ \text{Bond Order} = \frac{(\text{Number of electrons in bonding orbitals}) - (\text{Number of electrons in antibonding orbitals})}{2} \]

2. **Molecular Orbital Configuration of \( H_2 \)**:
- For \( H_2 \), the molecular orbital configuration is:
- Bonding orbital: \( \sigma_{1s} \) (2 electrons)
- Antibonding orbital: \( \sigma^*_{1s} \) (0 electrons)
- Thus, the bond order for \( H_2 \) is:
\[ \text{Bond Order} = \frac{2 - 0}{2} = 1 \]

3. **Molecular Orbital Configuration of \( H_2^+ \)**:
- \( H_2^+ \) has one less electron than \( H_2 \). Therefore, it has 1 electron in the bonding orbital \( \sigma_{1s} \) and 0 electrons in the antibonding orbital \( \sigma^*_{1s} \).
- The bond order for \( H_2^+ \) is calculated as follows:
\[ \text{Bond Order} = \frac{1 - 0}{2} = 0.5 \]

4. **Understanding the Reason (R)**:
- The reason states that electrons are removed from the antibonding molecular orbital of \( H_2 \).
- However, when forming \( H_2^+ \), the electron is actually removed from the bonding orbital \( \sigma_{1s} \), not from the antibonding orbital \( \sigma^*_{1s} \).

5. **Conclusion**:
- The assertion (A) is true because the bond order of \( H_2^+ \) is indeed 0.5.
- The reason (R) is false because electrons are not removed from the antibonding orbital.
- Therefore, the correct option is that the assertion is true but the reason is false.

### Final Answer:
The correct option is **3. Assertion is true but reason is false.**