Which of the following compound has twice the number of primary hydrogens as the number of secondary hydrogens ?

Options

A. `(CH_(3))_(2)C ClCH(CH_(3))_(2)`
B. `(CH_(3))_(3)C CH_(2)C(CH_(3))_(3)`
C. `(C_(2)H_(5))_(2)C(CH_(3))CH_(2)CH_(3)`
D. `(C_(2)H_(5))_(2)CHCH_(2)CH_(2)CH(CH_(3))_(2)`

Explanation

To solve the question of which compound has twice the number of primary hydrogens as the number of secondary hydrogens, we will analyze each option systematically.

### Step-by-Step Solution:

1. **Understanding Primary and Secondary Hydrogens**:
- **Primary Hydrogens**: These are hydrogens attached to primary carbons, which are carbons bonded to only one other carbon atom.
- **Secondary Hydrogens**: These are hydrogens attached to secondary carbons, which are carbons bonded to two other carbon atoms.

2. **Analyzing Each Option**:
- **Option A**:
- Structure: C (with Cl) - CH3 - CH2 - CH3
- Count the primary and secondary hydrogens:
- Primary Carbons: 4 (each CH3 contributes 3, and CH2 contributes 2)
- Secondary Carbons: 1 (the CH2 is secondary)
- Primary Hydrogens: 12 (3 from each of the 4 primary carbons)
- Secondary Hydrogens: 2 (from the secondary carbon)
- Ratio: 12 primary hydrogens / 2 secondary hydrogens = 6 (not 2:1)
- Conclusion: This option does not satisfy the condition.

- **Option B**:
- Structure: C - CH3 - CH2 - C - CH3
- Count the primary and secondary hydrogens:
- Primary Carbons: 5 (each CH3 contributes 3, and CH2 contributes 2)
- Secondary Carbons: 1 (the carbon connected to two CH3 groups)
- Primary Hydrogens: 18 (3 from each of the 6 primary carbons)
- Secondary Hydrogens: 2 (from the secondary carbon)
- Ratio: 18 primary hydrogens / 2 secondary hydrogens = 9 (not 2:1)
- Conclusion: This option does not satisfy the condition.

- **Option C**:
- Structure: C2H5 - CH3 - CH2 - CH3
- Count the primary and secondary hydrogens:
- Primary Carbons: 4 (the two CH3 groups and two CH2 groups)
- Secondary Carbons: 1 (the carbon connected to two CH3 groups)
- Primary Hydrogens: 12 (3 from each of the 4 primary carbons)
- Secondary Hydrogens: 6 (2 from the secondary carbon)
- Ratio: 12 primary hydrogens / 6 secondary hydrogens = 2 (this satisfies the condition)
- Conclusion: This option satisfies the condition.

- **Option D**:
- Structure: C2H5 - CH2 - CH3
- Count the primary and secondary hydrogens:
- Primary Carbons: 4 (each CH3 contributes 3, and CH2 contributes 2)
- Secondary Carbons: 1 (the CH2 is secondary)
- Primary Hydrogens: 12 (3 from each of the 4 primary carbons)
- Secondary Hydrogens: 4 (from the secondary carbon)
- Ratio: 12 primary hydrogens / 4 secondary hydrogens = 3 (not 2:1)
- Conclusion: This option does not satisfy the condition.

3. **Final Answer**:
- The compound that has twice the number of primary hydrogens as the number of secondary hydrogens is **Option C**.