When ethyl amine is heated with chloroform and alcoholic KOH, a compound with offensive smell is obtained. This compound is :

Options

A. A secondary amine
B. An isocyanide
C. A cyanide
D. An acid

Explanation

To solve the question, we need to understand the reaction that occurs when ethyl amine is heated with chloroform and alcoholic KOH. This reaction is known as the isocyanide test.

### Step-by-Step Solution:

1. **Identify the Reactants**:
- The reactants in this reaction are ethyl amine (C2H5NH2), chloroform (CHCl3), and alcoholic potassium hydroxide (KOH).

2. **Understand the Reaction Conditions**:
- When a primary amine (like ethyl amine) is treated with chloroform in the presence of a strong base (alcoholic KOH), it leads to the formation of isocyanides.

3. **Reaction Mechanism**:
- The mechanism involves the formation of an intermediate that reacts with chloroform and the base. The base deprotonates the amine, allowing it to react with chloroform to form an isocyanide.
- The reaction can be summarized as:
\[ \text{C2H5NH2} + \text{CHCl3} + \text{KOH} \rightarrow \text{C2H5N} \equiv \text{C} + \text{KCl} + \text{H2O} \]
- Here, ethyl isocyanide (C2H5N≡C) is formed, along with potassium chloride (KCl) and water (H2O).

4. **Identify the Product**:
- The product formed, ethyl isocyanide, is known for its offensive smell. This is a key characteristic of isocyanides.

5. **Conclusion**:
- Therefore, when ethyl amine is heated with chloroform and alcoholic KOH, the compound obtained is ethyl isocyanide, which is an isocyanide.

### Final Answer:
The compound with an offensive smell obtained from the reaction is **ethyl isocyanide** (option B: isocyanide).