In the structure of `4`-Isoropyl-`2,4,5`-trimethylheptane, number of `1^(@),2^(@)` & `3^(@) H's` are respectively.

Options

A. 18,5,4
B. 21,4,3
C. 18,4,3
D. 21,5,4

Explanation

To determine the number of 1°, 2°, and 3° hydrogens in the structure of 4-Isopropyl-2,4,5-trimethylheptane, we will follow these steps:

### Step 1: Understand the Structure
- **Heptane** indicates a straight-chain hydrocarbon with 7 carbon atoms.
- The compound has substituents at specific positions: isopropyl at position 4 and methyl groups at positions 2, 4, and 5.

### Step 2: Draw the Carbon Skeleton
- Draw the main chain of 7 carbons (heptane):
```
C1 - C2 - C3 - C4 - C5 - C6 - C7
```

### Step 3: Add Methyl Groups
- Add methyl groups (−CH₃) at positions 2, 4, and 5:
```
C1 - C2(CH₃) - C3 - C4(CH₃) - C5(CH₃) - C6 - C7
```

### Step 4: Add Isopropyl Group
- Add the isopropyl group (−CH(CH₃)₂) at position 4:
```
C1 - C2(CH₃) - C3 - C4(CH(CH₃)₂) - C5(CH₃) - C6 - C7
```

### Step 5: Identify Degree of Carbons
- **1° Carbon**: A carbon bonded to only one other carbon.
- **2° Carbon**: A carbon bonded to two other carbons.
- **3° Carbon**: A carbon bonded to three other carbons.

### Step 6: Count the Carbons
- **1° Carbons**: C1, C2 (methyl groups), C5 (methyl group), C6, C7 (total: 6)
- **2° Carbons**: C3 (connected to C2 and C4), C6 (connected to C5 and C7) (total: 2)
- **3° Carbons**: C4 (connected to C2, C3, and isopropyl group) (total: 1)

### Step 7: Count the Hydrogens
- **1° Hydrogens**: Each 1° carbon has 3 hydrogens (C1, C2, C5, C6, C7) = 6 carbons × 3 H = 18 H
- **2° Hydrogens**: Each 2° carbon has 2 hydrogens (C3, C6) = 2 carbons × 2 H = 4 H
- **3° Hydrogens**: Each 3° carbon has 1 hydrogen (C4) = 1 carbon × 1 H = 1 H

### Step 8: Total Count
- Total 1° H = 18
- Total 2° H = 4
- Total 3° H = 1

### Final Answer
The number of 1°, 2°, and 3° hydrogens in 4-Isopropyl-2,4,5-trimethylheptane are **18, 4, and 1**, respectively.

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