Which is most basic among the followings ?

Options

A. `Ph-NH_(2)`
B. `NH_(3)`
C. `CH_(3)-NH_(2)`
D. `C_(2)H_(5)-CN`

Answer

To determine which compound is the most basic among the given options, we will analyze the basicity of each compound step by step.

### Step 1: Identify the Compounds
The compounds given are:
1. **pH NH2** (aniline)
2. **NH3** (ammonia)
3. **CH3 NH2** (methylamine)
4. **C2H5 CN** (ethanenitrile)

### Step 2: Classify the Compounds
- **pH NH2** (aniline) is a primary amine.
- **NH3** (ammonia) is a simple amine.
- **CH3 NH2** (methylamine) is also a primary amine.
- **C2H5 CN** (ethanenitrile) is not an amine; it contains a cyanide group.

### Step 3: Eliminate Non-Amine Compound
Since C2H5 CN is not an amine, we can eliminate it from consideration. This leaves us with:
1. pH NH2 (aniline)
2. NH3 (ammonia)
3. CH3 NH2 (methylamine)

### Step 4: Compare Basicity of Ammonia and Primary Amines
It is known that primary amines (like CH3 NH2 and pH NH2) are generally more basic than ammonia (NH3). Thus, we can eliminate ammonia from being the most basic.

### Step 5: Compare Basicity of pH NH2 and CH3 NH2
Now we need to compare the basicity of the two primary amines:
- **pH NH2** (aniline) has a phenyl group (pH) attached to the nitrogen. The phenyl group is electron-withdrawing due to resonance, which delocalizes the lone pair of electrons on nitrogen, making them less available for protonation.
- **CH3 NH2** (methylamine) has a methyl group (CH3) attached to the nitrogen. The methyl group is electron-donating, which increases the availability of the lone pair of electrons on nitrogen for protonation.

### Step 6: Conclusion
Since the methyl group increases the basicity while the phenyl group decreases it, CH3 NH2 (methylamine) is more basic than pH NH2 (aniline). Therefore, the most basic compound among the given options is:

**Answer: CH3 NH2 (methylamine)**

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