Statement-I : Chlorination of ethyl benzene with `Cl_(2)` in presence of heat and light mainly yield 1-chloro-1-phenyl ethane as major product.
Because
Statement-II : The reaction oC Curs through intermediate formation of the radical `C_(6)H_(5)CH-CH_(3)`.

Answer

To solve the question, we need to analyze both Statement-I and Statement-II regarding the chlorination of ethyl benzene with Cl₂ in the presence of heat and light.

### Step-by-Step Solution:

1. **Understanding the Reaction**:
- Ethyl benzene (C₆H₅CH₂CH₃) is being chlorinated using chlorine gas (Cl₂) under heat and light conditions. This process typically involves a free radical mechanism.

**Hint**: Recall that chlorination reactions often proceed through free radical mechanisms, especially in the presence of heat and light.

2. **Formation of Free Radicals**:
- When Cl₂ is exposed to heat and light, it undergoes homolytic cleavage to form two chlorine radicals (Cl•). These radicals are highly reactive and can initiate the chlorination process.

**Hint**: Remember that free radicals are formed when bonds are broken homolytically, resulting in unpaired electrons.

3. **Attack on Ethyl Benzene**:
- The chlorine radical (Cl•) attacks the hydrogen atom of ethyl benzene, leading to the formation of a free radical intermediate. This intermediate is a benzylic radical (C₆H₅CH•CH₃), where the radical is located on the carbon adjacent to the benzene ring.

**Hint**: Identify the position of the radical after the hydrogen abstraction; it will be on the benzylic carbon.

4. **Stability of the Benzylic Radical**:
- The benzylic radical (C₆H₅CH•CH₃) is resonance-stabilized due to the adjacent aromatic ring. This stabilization makes it more favorable for the reaction to proceed through this intermediate.

**Hint**: Consider the stability of radicals; benzylic radicals are more stable than primary or secondary radicals due to resonance.

5. **Final Product Formation**:
- The chlorine radical can now react with the benzylic radical to form 1-chloro-1-phenyl ethane (C₆H₅C(Cl)HCH₃). This product is favored because it results from the most stable radical intermediate.

**Hint**: The final product is determined by the stability of the radical intermediate formed during the reaction.

6. **Conclusion**:
- Both statements are correct. Statement-I correctly identifies the major product of the reaction, and Statement-II provides the correct explanation for why that product is formed, specifically mentioning the formation of the benzylic radical.

### Final Answer:
Both Statement-I and Statement-II are true, and Statement-II is the correct explanation for Statement-I.