Which contenet (s) of middle oil separate on cooling?

Options

A. Napthalene
B. Phenol
C. Benzene
D. Pyride

Explanation

To solve the question "Which content(s) of middle oil separate on cooling?", we can follow these steps:

### Step 1: Understand the Composition of Middle Oil
Middle oil is one of the fractions obtained from the fractional distillation of coal tar. It typically contains three main components: naphthalene, pyridine, and phenol.

**Hint:** Remember the components of middle oil to identify which one separates on cooling.

### Step 2: Identify the Components
From the information provided, we know that:
- Naphthalene
- Pyridine
- Phenol

These are the components found in the middle oil.

**Hint:** List out the components to visualize which might have different physical properties, such as melting point.

### Step 3: Determine Which Component Separates on Cooling
Among the components of middle oil, naphthalene is known to solidify and separate out when the mixture is cooled. This is due to its relatively higher melting point compared to pyridine and phenol.

**Hint:** Consider the physical properties of each component, especially their melting points, to determine which one solidifies first.

### Step 4: Conclusion
Based on the analysis, the component that separates from the middle oil upon cooling is naphthalene.

**Final Answer:** The content that separates on cooling from middle oil is **naphthalene**.

### Summary of Steps:
1. Understand the composition of middle oil.
2. Identify the components present in middle oil.
3. Determine which component has the property of solidifying upon cooling.
4. Conclude that naphthalene separates on cooling.