Which is the correct stability order for the given carbonium ions?
A.Methyl B.ethyl C.iso-propyl D.tert-butyl

Options

A. `bgtagtcgtd`
B. `dgtcgtagtb`
C. `agtbgtcgtd`
D. `dgtcgtbgta`

Answer

To determine the stability order of the given carbonium ions (carbocations), we will analyze the stability based on the degree of substitution of the carbon atom bearing the positive charge. The stability of carbocations increases with the number of alkyl groups attached to the positively charged carbon atom due to hyperconjugation and the inductive effect.

### Step-by-Step Solution:

1. **Identify the Structures of the Carbocations:**
- **Methyl Carbocation (A)**: CH₃⁺
- **Ethyl Carbocation (B)**: CH₃CH₂⁺
- **Isopropyl Carbocation (C)**: (CH₃)₂CH⁺
- **Tert-butyl Carbocation (D)**: (CH₃)₃C⁺

2. **Determine the Degree of Each Carbocation:**
- **Methyl Carbocation (A)**: This is a primary carbocation (1°), as it has only one alkyl group attached.
- **Ethyl Carbocation (B)**: This is also a primary carbocation (1°), as it has two hydrogen atoms and one alkyl group.
- **Isopropyl Carbocation (C)**: This is a secondary carbocation (2°), as it has two alkyl groups attached to the positively charged carbon.
- **Tert-butyl Carbocation (D)**: This is a tertiary carbocation (3°), as it has three alkyl groups attached to the positively charged carbon.

3. **Stability Order Based on Degree of Substitution:**
- Tertiary (3°) > Secondary (2°) > Primary (1°) > Methyl (0°)
- Therefore, the stability order from most stable to least stable is:
- D (tert-butyl) > C (isopropyl) > B (ethyl) > A (methyl)

4. **Final Stability Order:**
- The correct stability order for the given carbonium ions is:
- D > C > B > A

### Conclusion:
The correct answer is option 4: DCBA.