Which of the following compounds does not dissolve in conc. `H_(2)SO_(4)` even on warming `?`

Options

A. Ethylene
B. Benzene
C. Hexane
D. Aniline

Explanation

To determine which compound does not dissolve in concentrated sulfuric acid (H₂SO₄) even on warming, we will analyze the behavior of each compound listed in the options.

### Step 1: Analyze Ethylene (C₂H₄)
- Ethylene (C₂H₄) is an alkene with a double bond.
- When treated with concentrated sulfuric acid, ethylene undergoes an electrophilic addition reaction.
- The double bond reacts with H⁺ from H₂SO₄, forming a carbocation intermediate, which then reacts with HSO₄⁻ to form an alkyl hydrogen sulfate.
- Therefore, ethylene is soluble in concentrated sulfuric acid.

**Hint:** Look for compounds that can react with H₂SO₄. Alkenes typically react due to their double bonds.

### Step 2: Analyze Benzene (C₆H₆)
- Benzene is an aromatic hydrocarbon.
- It undergoes electrophilic aromatic substitution when treated with concentrated sulfuric acid.
- The reaction leads to the formation of sulfonic acid derivatives (like benzene sulfonic acid).
- Hence, benzene is also soluble in concentrated sulfuric acid.

**Hint:** Aromatic compounds can undergo electrophilic substitution, indicating they can dissolve in concentrated acids.

### Step 3: Analyze Hexane (C₆H₁₄)
- Hexane is an alkane, which means it has only single bonds and no double bonds or functional groups that can react with H₂SO₄.
- Since hexane does not have any unsaturation, it does not react with concentrated sulfuric acid.
- Therefore, hexane does not dissolve in concentrated sulfuric acid.

**Hint:** Alkanes are generally unreactive towards concentrated acids due to the absence of reactive sites.

### Step 4: Analyze Aniline (C₆H₅NH₂)
- Aniline is an aromatic amine.
- It can undergo electrophilic aromatic substitution with concentrated sulfuric acid, similar to benzene.
- The amino group (NH₂) is an electron-donating group, making the aromatic ring more reactive.
- Thus, aniline is also soluble in concentrated sulfuric acid.

**Hint:** Functional groups like amines can also participate in reactions with acids, leading to solubility.

### Conclusion
After analyzing all the compounds:
- Ethylene, benzene, and aniline all dissolve in concentrated sulfuric acid.
- Hexane does not dissolve in concentrated sulfuric acid, even on warming.

**Final Answer:** The compound that does not dissolve in concentrated H₂SO₄ even on warming is **Hexane (C₆H₁₄)**.