How many assymmetric carbon atoms are present in
(i)1,2-Dimethyl cyclohexane , (ii)3-Methyl cyclopentene , (iii)3-Methylcyclohexene

Options

A. 2,1,1
B. 1,1,1
C. 2,0,2
D. 2,0,1

Explanation

To determine the number of asymmetric (chiral) carbon atoms in the given compounds, we will analyze each structure step by step.

### Step 1: Analyze 1,2-Dimethylcyclohexane

1. **Draw the structure**: Start with a cyclohexane ring and add two methyl groups at the 1 and 2 positions.
2. **Identify chiral centers**:
- The carbon at position 1 has one hydrogen, one methyl group, and two other groups from the cyclohexane ring, making it chiral.
- The carbon at position 2 also has one hydrogen, one methyl group, and two other groups from the cyclohexane ring, making it chiral.
3. **Count the chiral centers**: There are **2 chiral centers** in 1,2-Dimethylcyclohexane.

### Step 2: Analyze 3-Methylcyclopentene

1. **Draw the structure**: Start with a cyclopentene ring and add a methyl group at the 3 position.
2. **Identify chiral centers**:
- The carbon at position 1 (part of the double bond) cannot be chiral.
- The carbon at position 2 (part of the double bond) cannot be chiral.
- The carbon at position 3 has one hydrogen, one methyl group, and two other groups from the cyclopentene ring, making it chiral.
- The other carbons in the ring do not have four different substituents.
3. **Count the chiral centers**: There is **1 chiral center** in 3-Methylcyclopentene.

### Step 3: Analyze 3-Methylcyclohexene

1. **Draw the structure**: Start with a cyclohexene ring and add a methyl group at the 3 position.
2. **Identify chiral centers**:
- The carbon at position 1 (part of the double bond) cannot be chiral.
- The carbon at position 2 (part of the double bond) cannot be chiral.
- The carbon at position 3 has one hydrogen, one methyl group, and two other groups from the cyclohexene ring, making it chiral.
- The other carbons in the ring do not have four different substituents.
3. **Count the chiral centers**: There is **1 chiral center** in 3-Methylcyclohexene.

### Final Count of Chiral Centers

- **1,2-Dimethylcyclohexane**: 2 chiral centers
- **3-Methylcyclopentene**: 1 chiral center
- **3-Methylcyclohexene**: 1 chiral center

### Summary

- Total chiral centers:
- 1,2-Dimethylcyclohexane: 2
- 3-Methylcyclopentene: 1
- 3-Methylcyclohexene: 1

### Answer:

The total number of asymmetric carbon atoms is:
- 2 (1,2-Dimethylcyclohexane)
- 1 (3-Methylcyclopentene)
- 1 (3-Methylcyclohexene)