Among the following compounds ,the strongest base is

Options

A. `NH_2-overset(O)overset(||)C-NH_2`
B. `NH_2-overset(NH)overset(||)C-NH_2`
C. `C_6H_5-NH_2`
D. `CH_3-NH-CH_3`

Answer

To determine the strongest base among the given compounds, we will analyze each compound based on the number of lone pairs of electrons present on the nitrogen atoms, as bases are defined by their ability to donate electron pairs according to the Lewis concept.

### Step-by-Step Solution:

1. **Identify the Compounds:**
Let's denote the compounds as:
- Compound 1: A
- Compound 2: B
- Compound 3: C
- Compound 4: D

2. **Analyze Each Compound:**
We need to look at the nitrogen atoms in each compound and count the number of lone pairs of electrons they have.

- **Compound A:** Contains 2 nitrogen atoms. Each nitrogen has 1 lone pair.
- Total lone pairs = 2 (1 from each nitrogen).

- **Compound B:** Contains 3 nitrogen atoms. Each nitrogen has 1 lone pair.
- Total lone pairs = 3 (1 from each nitrogen).

- **Compound C:** Contains 1 nitrogen atom with 1 lone pair.
- Total lone pairs = 1.

- **Compound D:** Contains 1 nitrogen atom with 1 lone pair.
- Total lone pairs = 1.

3. **Compare the Number of Lone Pairs:**
Now, we compare the total number of lone pairs in each compound:
- Compound A: 2 lone pairs
- Compound B: 3 lone pairs
- Compound C: 1 lone pair
- Compound D: 1 lone pair

4. **Determine the Strongest Base:**
According to the Lewis concept, the base that can donate the most electron pairs (i.e., has the most lone pairs) is the strongest base.
- Compound B has the highest number of lone pairs (3) compared to the others.

5. **Conclusion:**
Therefore, the strongest base among the given compounds is **Compound B**.

### Final Answer:
The strongest base is **Compound B**.