Correct order of basic strength is :-
(I) `CH_(3)-overset(O)overset(||)C-NH_(2)` (II) `C_(6)H_(5)-NH_(2)`
(III) `H_(2)N-overset(NH)overset(||)C-NH_(2)` (IV) `C_(6)H_(5)-overset(O)overset(||)C-NHCHO`

Options

A. `IgtIIIgtIIgtIV`
B. `IIgtIgtIIIgtIV`
C. `IIIgtIIgtIgtIV`
D. `IIIgtIgtIVgtII`

Answer

To determine the correct order of basic strength among the given compounds, we need to analyze each compound's structure and the factors that influence basicity.

### Step-by-step Solution:

1. **Identify the Compounds**:
- (I) `CH₃-C(=O)-NH₂` (Acetamide)
- (II) `C₆H₅-NH₂` (Aniline)
- (III) `H₂N-NH-C(=NH)-NH₂` (Urea derivative)
- (IV) `C₆H₅-C(=O)-NHCHO` (Benzoylurea)

2. **Analyze Basicity**:
Basicity in amines is influenced by the availability of the lone pair of electrons on the nitrogen atom. Electron-withdrawing groups (EWGs) decrease basicity, while electron-donating groups (EDGs) increase it.

3. **Evaluate Each Compound**:
- **Compound I (Acetamide)**: The carbonyl group (C=O) is an EWG, which reduces the availability of the nitrogen's lone pair, making it less basic.
- **Compound II (Aniline)**: The phenyl group (C₆H₅) is a weak EWG, but it allows some resonance stabilization of the lone pair on nitrogen, making it more basic than acetamide.
- **Compound III (Urea derivative)**: This compound has three nitrogen atoms, and the presence of multiple amine groups increases basicity. The nitrogen atoms can share their lone pairs, making it the most basic among the four.
- **Compound IV (Benzoylurea)**: Similar to acetamide, it has a carbonyl group that withdraws electron density from the nitrogen, making it less basic. However, the presence of the benzene ring also contributes to resonance, but overall it remains less basic than aniline.

4. **Rank the Compounds**:
- **Most Basic**: (III) `H₂N-NH-C(=NH)-NH₂` (due to three nitrogen atoms)
- **Next**: (II) `C₆H₅-NH₂` (aniline)
- **Then**: (I) `CH₃-C(=O)-NH₂` (acetamide)
- **Least Basic**: (IV) `C₆H₅-C(=O)-NHCHO` (benzoylurea)

5. **Final Order of Basic Strength**:
The correct order of basic strength is:
**(III) > (II) > (I) > (IV)**