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 analyze the given statements about carbon tetrabromide (CBr₄) and carbon tetraiodide (CI₄), we will break down the assertion and reason step by step.

### Step 1: Understanding the Assertion
The assertion states that CBr₄ is thermally more stable than CI₄.

**Explanation**:
Thermal stability refers to the ability of a compound to withstand heat without decomposing. In this case, we need to compare the stability of CBr₄ and CI₄ when subjected to heat.

### Step 2: Understanding the Reason
The reason states that the C-Br bond energy is greater than the C-I bond energy.

**Explanation**:
Bond energy is the amount of energy required to break a bond between two atoms. A higher bond energy indicates a stronger bond, which contributes to the overall stability of the molecule.

### Step 3: Analyzing Bond Energies
- The bond energy of C-Br is indeed higher than that of C-I. This is because as we move down the group in the periodic table, the size of the halogen atoms increases, leading to longer bond lengths and weaker bonds.
- C-Br bond involves the overlap of 2p (from carbon) and 4p (from bromine), while C-I bond involves 2p (from carbon) and 5p (from iodine). The larger size of iodine leads to a weaker bond due to less effective overlap.

### Step 4: Conclusion
Since CBr₄ has stronger C-Br bonds compared to the C-I bonds in CI₄, it is thermally more stable. Therefore, both the assertion and reason are correct, and the reason correctly explains the assertion.

### Final Answer
Both the assertion (A) and reason (R) are true, and R is the correct explanation of A.

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