The bond angles of alkenes and alkynes with two carbon atoms are

Options

A. `120^@` and `120^@` respectively
B. `120^@` and `180^@` respectively
C. `109^@` and `180^@` respectively
D. `109^@` and `120^@` respectively

Answer

To determine the bond angles of alkenes and alkynes with two carbon atoms, we need to analyze the hybridization of the carbon atoms in each case.

### Step-by-Step Solution:

1. **Identify the Type of Hydrocarbon**:
- Alkenes contain at least one carbon-carbon double bond (C=C).
- Alkynes contain at least one carbon-carbon triple bond (C≡C).

2. **Determine Hybridization in Alkenes**:
- In alkenes, the carbon atoms involved in the double bond are sp² hybridized.
- Each sp² hybridized carbon forms three sigma (σ) bonds: two with hydrogen atoms and one with another carbon atom.

3. **Calculate Bond Angle for Alkenes**:
- The geometry around sp² hybridized carbon is trigonal planar.
- The bond angles in a trigonal planar arrangement are approximately 120 degrees.

4. **Determine Hybridization in Alkynes**:
- In alkynes, the carbon atoms involved in the triple bond are sp hybridized.
- Each sp hybridized carbon forms two sigma (σ) bonds: one with another carbon atom and one with a hydrogen atom.

5. **Calculate Bond Angle for Alkynes**:
- The geometry around sp hybridized carbon is linear.
- The bond angles in a linear arrangement are 180 degrees.

6. **Summarize the Bond Angles**:
- For alkenes (C=C), the bond angle is 120 degrees.
- For alkynes (C≡C), the bond angle is 180 degrees.

### Final Answer:
- The bond angles of alkenes and alkynes with two carbon atoms are 120 degrees and 180 degrees, respectively.