Which compound is used for increase of octane rating?

Question

Which compound is used for increase of octane rating?

1. A. Trimethyl hexane
2. B. Tetramethyl Oxide
3. C. Tetraethyllead (Correct answer)
4. D. Triethyl toluene

Correct Answer

Option C — Tetraethyllead

Detailed Solution & Explanation

The correct answer is Tetraethyllead.

Key Points

• Tetraethyllead (TEL), with the formula Pb(C₂H₅)₄, was historically added to petrol as an anti-knocking agent to raise its octane rating.
• The octane number measures a fuel's resistance to premature ignition, or knocking, in an internal combustion engine.
• By convention, iso-octane is assigned an octane number of 100 and n-heptane is assigned 0.
• A higher octane rating means the fuel can withstand greater compression before igniting spontaneously.
• Tetraethyllead was phased out worldwide because it released lead into the atmosphere, causing severe neurological damage, especially in children, and because it poisoned the catalytic converters fitted to modern vehicles.
• India completed the transition to unleaded petrol in 2000.
• Modern refineries instead use oxygenates and reformulated blends such as MTBE and ethanol to boost octane.

Exam Tip

• link this to the cetane number, the corresponding quality rating for diesel.

प्रश्न (हिन्दी में)

ऑक्टेन रेटिंग बढ़ाने के लिए किस यौगिक का उपयोग किया जाता है?

1. A. ट्राइमेथिल हेक्सेन
2. B. टेट्रामिथाइल ऑक्साइड
3. C. टेट्राएथिललेड
4. D. ट्राइएथिल टोल्यूनि