Which of the following are isoelectronic species?
`overset(+)(CH_(3))`
II . `NH_(2)^(-)`
III . `NH_(4)^(+)`
IV `NH_(3)`

Options

A. I , II and III
B. II ,III and IV
C. I , II and IV
D. II and I

Explanation

To determine which of the given species are isoelectronic, we need to calculate the total number of electrons for each species. Isoelectronic species are those that have the same number of electrons.

### Step-by-Step Solution:

1. **Calculate the number of electrons in `CH₃⁺`:**
- Carbon (C) has 6 electrons.
- Each Hydrogen (H) has 1 electron, and there are 3 Hydrogens, contributing a total of 3 electrons.
- The positive charge indicates the loss of 1 electron.
- Total electrons = 6 (C) + 3 (H) - 1 (charge) = 8 electrons.

2. **Calculate the number of electrons in `NH₂⁻`:**
- Nitrogen (N) has 7 electrons.
- Each Hydrogen (H) has 1 electron, and there are 2 Hydrogens, contributing a total of 2 electrons.
- The negative charge indicates the gain of 1 electron.
- Total electrons = 7 (N) + 2 (H) + 1 (charge) = 10 electrons.

3. **Calculate the number of electrons in `NH₄⁺`:**
- Nitrogen (N) has 7 electrons.
- Each Hydrogen (H) has 1 electron, and there are 4 Hydrogens, contributing a total of 4 electrons.
- The positive charge indicates the loss of 1 electron.
- Total electrons = 7 (N) + 4 (H) - 1 (charge) = 10 electrons.

4. **Calculate the number of electrons in `NH₃`:**
- Nitrogen (N) has 7 electrons.
- Each Hydrogen (H) has 1 electron, and there are 3 Hydrogens, contributing a total of 3 electrons.
- Total electrons = 7 (N) + 3 (H) = 10 electrons.

### Summary of Electron Counts:
- `CH₃⁺`: 8 electrons
- `NH₂⁻`: 10 electrons
- `NH₄⁺`: 10 electrons
- `NH₃`: 10 electrons

### Conclusion:
The species that are isoelectronic (having the same number of electrons) are `NH₂⁻`, `NH₄⁺`, and `NH₃`, which all have 10 electrons. Therefore, the correct answer is that the isoelectronic species are II, III, and IV.