The shape of `CH_3^(+) and CH_3^(-)` is respectively

Options

A. plner,planer
B. plner,pyramidal
C. pyramidal,pyramidal
D. pyramidal,planer

Answer

To determine the shapes of the ions \( CH_3^+ \) (methyl cation) and \( CH_3^- \) (methyl anion), we need to analyze their hybridization and molecular geometry.

### Step-by-Step Solution:

1. **Identify the Hybridization of \( CH_3^+ \)**:
- The methyl cation \( CH_3^+ \) has one less electron than neutral methane \( CH_4 \).
- It has three hydrogen atoms and a positive charge, which means it has a total of 6 valence electrons (4 from carbon and 3 from hydrogen, minus 1 for the positive charge).
- The carbon atom in \( CH_3^+ \) forms three sigma bonds with the hydrogen atoms and has no lone pairs.
- Therefore, the hybridization is \( sp^2 \) because it uses three \( sp^2 \) hybrid orbitals to form these bonds.

**Shape**: The geometry of \( sp^2 \) hybridized molecules is trigonal planar.

2. **Identify the Hybridization of \( CH_3^- \)**:
- The methyl anion \( CH_3^- \) has one extra electron compared to neutral methane \( CH_4 \).
- It has three hydrogen atoms and a negative charge, which means it has a total of 8 valence electrons (4 from carbon and 3 from hydrogen, plus 1 for the negative charge).
- The carbon atom in \( CH_3^- \) forms three sigma bonds with the hydrogen atoms and has one lone pair.
- Therefore, the hybridization is \( sp^3 \) because it uses four \( sp^3 \) hybrid orbitals (three for bonding and one for the lone pair).

**Shape**: The geometry of \( sp^3 \) hybridized molecules is tetrahedral, but due to the presence of the lone pair, the shape is described as trigonal pyramidal.

### Final Answer:
- The shape of \( CH_3^+ \) is **trigonal planar**.
- The shape of \( CH_3^- \) is **trigonal pyramidal**.