Which of the following is used as an anti-knocking material ?

Options

A. Glyoxal
B. Freon
C. T.E.L.
D. Ethyl alcohol

Answer

To determine which of the following is used as an anti-knocking material, we can follow these steps:

### Step 1: Understand the Concept of Anti-Knocking Material
An anti-knocking material is a chemical compound added to fuel to prevent engine knocking. Engine knocking is an undesirable phenomenon that occurs due to premature combustion in the engine, leading to a sharp sound and potential engine damage.

**Hint:** Look for terms related to fuel additives that help in reducing engine knocking.

### Step 2: Identify Common Anti-Knocking Agents
The most common anti-knocking agent historically used in the industry is Tetraethyl Lead (TEL). It was widely used to enhance the octane rating of gasoline, thereby reducing knocking.

**Hint:** Research or recall the names of compounds that are known for their use in gasoline to improve performance.

### Step 3: Analyze Other Options
In the context of the question, consider other substances mentioned:
- Freon (CFCs) is a refrigerant and not related to fuel performance.
- Ethyl Alcohol (Ethanol) is sometimes blended with gasoline but primarily serves to enhance fuel properties rather than directly acting as an anti-knock agent.

**Hint:** Eliminate options that do not directly relate to reducing engine knocking.

### Step 4: Conclude the Answer
Based on the information gathered, Tetraethyl Lead (TEL) is the correct answer as it is specifically recognized as an anti-knocking agent used in fuels.

**Final Answer:** Tetraethyl Lead (TEL) is used as an anti-knocking material.