To which of the following compounds `H_(2)` adds most readily?

Options

A. `CH_(2)=CH_(2)`
B. `CH_(3)-CH=CH_(2)`
C. `CH_(3)-CH=CH-CH_(3)`
D. `CH_(3)-underset(CH_(3))underset(|)(C)=CH-CH_(3)`

Answer

To determine which compound \( H_2 \) adds to most readily, we need to analyze the stability of the alkenes provided. The reactivity of alkenes towards hydrogenation (addition of \( H_2 \)) is inversely related to their stability.

### Step-by-Step Solution:

1. **Identify the Compounds**: List the given compounds (alkenes). For this example, let's assume they are:
- Ethene (C2H4) - no substituents
- Propene (C3H6) - one substituent
- Butene (C4H8) - two substituents
- Isobutene (C4H8) - three substituents

2. **Determine Substitution**: Identify the degree of substitution for each alkene:
- Ethene: 0 substituents (least stable)
- Propene: 1 substituent (more stable than ethene)
- Butene: 2 substituents (more stable than propene)
- Isobutene: 3 substituents (most stable)

3. **Stability Order**: Arrange the alkenes in order of stability based on the number of substituents:
- Most stable: Isobutene (3 substituents)
- Next: Butene (2 substituents)
- Then: Propene (1 substituent)
- Least stable: Ethene (0 substituents)

4. **Reactivity Order**: Since stability is inversely proportional to reactivity, we can derive the reactivity order:
- Most reactive: Ethene (least stable)
- Next: Propene
- Then: Butene
- Least reactive: Isobutene (most stable)

5. **Conclusion**: Since ethene is the most reactive alkene, it will add \( H_2 \) most readily. Therefore, the correct answer is:
- **Ethene (Option 1)**