The increasing order of basicity of `RCN,RCH=NR` and `RNH_(2)` is :-

Options

A. `RCNltRCH=NRltRNH_(2)`
B. `RNH_(2)ltRCNltRCH=NR`
C. `RCH=NRltRNH_(2)ltRCN`
D. `RH_(2)NltRCH=NRltRCN`

Answer

To determine the increasing order of basicity of the compounds RCN, RCH=NR, and RNH2, we need to analyze the hybridization and the electron-donating ability of the nitrogen atom in each compound.

### Step-by-Step Solution:

1. **Identify the Hybridization of Nitrogen in Each Compound**:
- In **RCN** (nitrile), the nitrogen is **sp hybridized**.
- In **RCH=NR** (imines), the nitrogen is **sp² hybridized**.
- In **RNH2** (amines), the nitrogen is **sp³ hybridized**.

2. **Understand the Relationship Between Hybridization and Basicity**:
- The basicity of a compound is influenced by the ability of the nitrogen atom to donate its lone pair of electrons.
- **sp hybridized** nitrogen has the highest s-character (50%), making it more electronegative and less willing to donate its electrons. Thus, it is the least basic.
- **sp² hybridized** nitrogen has 33% s-character, making it less electronegative than sp hybridized nitrogen, and thus more basic than RCN.
- **sp³ hybridized** nitrogen has the lowest s-character (25%) and is the least electronegative, making it the most basic of the three.

3. **Rank the Compounds Based on Basicity**:
- Since RCN is the least basic (due to sp hybridization), followed by RCH=NR (sp²), and RNH2 being the most basic (sp³), we can establish the order:
- **RCN < RCH=NR < RNH2**

### Final Answer:
The increasing order of basicity is:
**RCN < RCH=NR < RNH2**