A : `CBr_(4)` is thermally more stable than `Cl_(4)` .
R : C- Br bond energy is more than C-l

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 assertion-reason question regarding the thermal stability of \( CBr_4 \) compared to \( CI_4 \), we will analyze both the assertion and the reason step by step.

### Step 1: Understand the Assertion
The assertion states that \( CBr_4 \) is thermally more stable than \( CI_4 \).

**Hint:** Consider the factors that contribute to thermal stability in chemical compounds, such as bond strength and molecular structure.

### Step 2: Analyze the Structures
Both \( CBr_4 \) and \( CI_4 \) are tetrahedral in shape due to the sp³ hybridization of carbon.

- **Structure of \( CBr_4 \)**: Contains four bromine atoms.
- **Structure of \( CI_4 \)**: Contains four iodine atoms.

**Hint:** Recall that the size of the halogen atoms (bromine vs. iodine) plays a crucial role in the properties of the compounds.

### Step 3: Compare the Bond Lengths
Bromine (Br) is smaller in atomic radius compared to iodine (I). This means that the \( C-Br \) bond will be shorter than the \( C-I \) bond.

**Hint:** Remember that shorter bonds are generally stronger due to the increased overlap of atomic orbitals.

### Step 4: Compare the Bond Strengths
Since the \( C-Br \) bond is shorter, it is also stronger than the \( C-I \) bond. Stronger bonds contribute to greater thermal stability.

**Hint:** Think about how bond strength affects the energy required to break the bonds in a molecule.

### Step 5: Conclusion on Assertion
Since \( CBr_4 \) has stronger \( C-Br \) bonds compared to the \( C-I \) bonds in \( CI_4 \), it follows that \( CBr_4 \) is thermally more stable than \( CI_4 \). Therefore, the assertion is correct.

### Step 6: Analyze the Reason
The reason states that the \( C-Br \) bond energy is greater than the \( C-I \) bond energy.

**Hint:** Consider how bond energy relates to bond length and bond strength.

### Step 7: Conclusion on Reason
The reason is also correct because the smaller size of bromine leads to stronger \( C-Br \) bonds, which indeed have higher bond energy compared to \( C-I \) bonds.

### Final Conclusion
Both the assertion and the reason are correct, and the reason provides a valid explanation for the assertion.