Basic strength of
`H_2"CC"H_3`
`H_2C= CH_(2)`
`H-C-= C-H`

Options

A. `(i) gt (iii) gt (ii)`
B. `(i) gt (ii) gt (iii)`
C. `(ii) gt (i) gt (iii)`
D. `(iii) gt (iii) gt (i)`

Explanation

To determine the basic strength of the given hydrocarbons:

1. **Identify the Compounds**: The compounds given are:
- Compound 1: Ethane (H₂C=CH₃)
- Compound 2: Ethene (H₂C=CH₂)
- Compound 3: Ethyne (H-C≡C-H)

2. **Understand Basic Strength**: The basic strength of hydrocarbons is influenced by their hybridization and the percentage of s-character in their hybrid orbitals. The more s-character in the hybrid orbital, the more acidic the compound is, which inversely affects its basic strength.

3. **Determine Hybridization**:
- For Ethane (H₂C=CH₃):
- It has 4 sigma bonds (3 from H and 1 from C) and 0 lone pairs.
- Hybridization: SP³ (4 sigma bonds)
- % s-character = 25%

- For Ethene (H₂C=CH₂):
- It has 3 sigma bonds (2 from H and 1 from C) and 0 lone pairs.
- Hybridization: SP² (3 sigma bonds)
- % s-character = 33.3%

- For Ethyne (H-C≡C-H):
- It has 2 sigma bonds (1 from H and 1 from C) and 0 lone pairs.
- Hybridization: SP (2 sigma bonds)
- % s-character = 50%

4. **Analyze Basic Strength**:
- As the % s-character increases, the basic strength decreases.
- Ethane (25% s-character) has the least s-character and is the most basic.
- Ethene (33.3% s-character) is less basic than Ethane.
- Ethyne (50% s-character) has the most s-character and is the least basic.

5. **Order of Basic Strength**:
- Ethane (most basic) > Ethene > Ethyne (least basic)

6. **Final Answer**: The order of basic strength is:
- Ethane > Ethene > Ethyne