The decreasing order of the basic character of `NH_(3), CH_(3)NH_(2), C_(2)H_(5)NH_(2)` and `C_(6)H_(5)NH_(2)` is

Options

A. `NH_(3) gt CH_(3)NH_(2) gt C_(2)H_(5)NH_(2) gt C_(6)H_(5)NH_(2)`
B. `C_(2)H_(5)NH_(2) gt CH_(3)NH_(2) gt NH_(3) gt C_(6)H_(5)NH_(2)`
C. `C_(6)H_(5)NH_(2) gt C_(2)H_(5)NH_(2) gt CH_(3)NH_(2) gt NH_(3)`
D. `CH_(3)NH_(2) gt C_(2)H_(5)NH_(2) gt C_(6)H_(5)NH_(2) gt NH_(3)`

Answer

To determine the decreasing order of the basic character of the compounds NH₃ (ammonia), CH₃NH₂ (methylamine), C₂H₅NH₂ (ethylamine), and C₆H₅NH₂ (aniline), we will analyze the factors affecting the basicity of these amines.

### Step-by-Step Solution:

1. **Understanding Basicity**: Basicity in amines is associated with the availability of the lone pair of electrons on the nitrogen atom. The more available the lone pair is for donation, the stronger the base.

2. **Effect of Alkyl Groups**: Alkyl groups are electron-donating due to the +I (inductive) effect. This increases the electron density on the nitrogen atom, enhancing its ability to donate the lone pair.

3. **Comparing Methylamine and Ethylamine**:
- **Methylamine (CH₃NH₂)**: The methyl group (CH₃) has a +I effect, which increases the electron density on nitrogen.
- **Ethylamine (C₂H₅NH₂)**: The ethyl group (C₂H₅) has a stronger +I effect compared to the methyl group. Therefore, ethylamine has more electron density on nitrogen than methylamine, making ethylamine a stronger base than methylamine.

4. **Comparing Ammonia with Methylamine and Ethylamine**:
- **Ammonia (NH₃)**: Ammonia has no alkyl groups to increase the electron density on nitrogen. Thus, it is less basic than both methylamine and ethylamine.

5. **Analyzing Aniline**:
- **Aniline (C₆H₅NH₂)**: In aniline, the lone pair of electrons on nitrogen is partially delocalized into the benzene ring due to resonance. This delocalization decreases the availability of the lone pair for donation, making aniline a weaker base than ammonia, methylamine, and ethylamine.

6. **Conclusion**: Based on the above analysis, we can summarize the basicity in the following order:
- Ethylamine (C₂H₅NH₂) > Methylamine (CH₃NH₂) > Ammonia (NH₃) > Aniline (C₆H₅NH₂)

### Final Answer:
The decreasing order of the basic character is:
**C₂H₅NH₂ > CH₃NH₂ > NH₃ > C₆H₅NH₂**