Assertion (A) Toluene on Friedal Crafts methylation gives o - and p-xylene.
Reason ( R) `CH_(3)`-group bonded to benzene ring increases density at o - and p- position.

Options

A. Both A and B are correct and R is the correct explanation of A
B. Both A and R are not correct
C. Both A and R are not correct
D. A is not correct but R is correct

Explanation

### Step-by-Step Solution:

1. **Understanding Toluene Structure**:
- Toluene is a methyl-substituted benzene, represented as C6H5-CH3. The methyl (CH3) group is attached to one of the carbon atoms of the benzene ring.

2. **Friedel-Crafts Methylation**:
- In Friedel-Crafts methylation, we use a methyl halide (like CH3Cl) and a Lewis acid catalyst (like AlCl3) to introduce a methyl group onto the benzene ring.

3. **Electrophile Formation**:
- The reaction generates a methyl cation (CH3+) as the electrophile, which will react with the benzene ring.

4. **Electron-Donating Effect of the Methyl Group**:
- The methyl group exhibits a +I (inductive) effect, meaning it donates electron density to the benzene ring. This makes the ortho (adjacent) and para (opposite) positions more electron-rich and thus more reactive towards electrophiles.

5. **Ortho and Para Directing**:
- Due to the +I effect and hyperconjugation, the methyl group directs incoming electrophiles to the ortho and para positions. This is because these positions can stabilize the positive charge that develops during the formation of the sigma complex (the intermediate in electrophilic aromatic substitution).

6. **Products Formation**:
- The reaction leads to the formation of two products: ortho-xylene (1,2-dimethylbenzene) and para-xylene (1,4-dimethylbenzene).

7. **Conclusion**:
- Therefore, the assertion that toluene on Friedel-Crafts methylation gives ortho and para-xylene is correct. The reason provided, that the CH3 group increases electron density at the ortho and para positions, is also correct and explains why the reaction favors these positions.

### Final Answer:
Both the assertion (A) and the reason (R) are correct, and the reason (R) correctly explains the assertion (A).

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