In the given reaction `C_6H_5-CH_2-CH_3overset(NBS)rarr(X)overset(Alc.KOH//Delta)rarr(Y)` In the given reaction X and Y respectively are

Options

A. `C_6H_5-CHBr-CH_3 and C_6H_5-C-=CH`
B. `C_6H_5-CBr_2-CH_3 and C_6H_5-C-=CH`
C. `C_6H_5-CBr_2-CH_3 and C_6H_5-CBr-=CH_2`
D. `C_6H_5-CHBr-CH_3and C_6H_5-CH=CH_2`

Answer

To solve the question regarding the reaction involving N-bromosuccinimide (NBS) and alcoholic KOH, we will break down the steps involved in the reaction to identify the compounds X and Y.

### Step-by-Step Solution:

**Step 1: Identify the starting compound**
- The starting compound is `C6H5-CH2-CH3`, which is ethylbenzene.

**Step 2: Reaction with N-bromosuccinimide (NBS)**
- N-bromosuccinimide is used to brominate the benzylic position of the ethylbenzene. This reaction proceeds via a free radical mechanism.
- The hydrogen atom from the benzylic position (the `CH2` group) is abstracted by a bromine radical (Br•), generating a benzylic radical.

**Step 3: Formation of the benzylic radical**
- The structure of the benzylic radical formed is `C6H5-CH•-CH3`. This radical is stabilized by resonance due to the adjacent aromatic ring, which allows for multiple resonance structures.

**Step 4: Bromination of the benzylic radical**
- The benzylic radical then reacts with another bromine atom from NBS to form the benzylic bromide, `C6H5-CHBr-CH3`. This compound is our product X.

**Step 5: Reaction with alcoholic KOH**
- The next step involves treating the benzylic bromide with alcoholic KOH. Alcoholic KOH acts as a strong base and facilitates dehydrohalogenation.
- The base abstracts a hydrogen atom from the beta position (the `CH3` group), leading to the elimination of HBr and the formation of a double bond.

**Step 6: Formation of the alkene**
- The product formed after dehydrohalogenation is `C6H5-CH=CH2`. This compound is our product Y, which is an alkene.

### Final Products:
- Therefore, the compounds X and Y are:
- **X**: `C6H5-CHBr-CH3` (benzylic bromide)
- **Y**: `C6H5-CH=CH2` (alkene)

### Conclusion:
The answer to the question is:
- **X**: `C6H5-CHBr-CH3`
- **Y**: `C6H5-CH=CH2`