Arrange the following in increasing order of basic strength:
Aniline, p-nitroaniline and p-toludine.

Options

A. Aniline `lt `p-Nitroaniline `lt `p-Toluidine
B. Aniline `lt `p-Toluidine `lt `p-Nitroaniline
C. p-Toluidine `lt `p-Nitroaniline `lt` Aniline
D. p-Nitroaniline `lt` Aniline `lt`p-Toluidine

Explanation

To determine the increasing order of basic strength for aniline, p-nitroaniline, and p-toluidine, we need to analyze the effects of substituents on the basicity of these compounds.

### Step 1: Understand Basicity
Basicity in amines is influenced by the availability of the lone pair of electrons on the nitrogen atom. The more available the lone pair is, the stronger the base. Electron-donating groups increase basicity, while electron-withdrawing groups decrease it.

### Step 2: Draw the Structures
1. **Aniline (C6H5NH2)**: This is the simplest amine with an amino group (-NH2) directly attached to a benzene ring.
2. **p-Nitroaniline (C6H4(NH2)(NO2))**: This compound has a nitro group (-NO2) at the para position relative to the amino group. The nitro group is an electron-withdrawing group.
3. **p-Toluidine (C6H4(NH2)(CH3))**: This compound has a methyl group (-CH3) at the para position relative to the amino group. The methyl group is an electron-donating group.

### Step 3: Analyze the Effects of Substituents
- **Aniline**: The amino group is directly attached to the benzene ring and has moderate basicity.
- **p-Nitroaniline**: The nitro group withdraws electron density from the ring, which decreases the electron density on the nitrogen atom. This makes it less basic than aniline.
- **p-Toluidine**: The methyl group donates electron density to the ring, increasing the electron density on the nitrogen atom. This makes it more basic than aniline.

### Step 4: Compare Basic Strengths
- **p-Nitroaniline**: Least basic due to the strong electron-withdrawing effect of the nitro group.
- **Aniline**: Moderate basicity.
- **p-Toluidine**: Most basic due to the electron-donating effect of the methyl group.

### Step 5: Arrange in Increasing Order
Based on the analysis:
1. p-Nitroaniline (least basic)
2. Aniline (moderate basic)
3. p-Toluidine (most basic)

Thus, the increasing order of basic strength is:
**p-Nitroaniline < Aniline < p-Toluidine**

### Final Answer
**p-Nitroaniline < Aniline < p-Toluidine**

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