Tetra methyl lead is added to petrol to:
Correct answer: C. Prevent knocking
- A. Prevent its freezing point
- B. Increase its boiling point
- C. Prevent knocking
- D. Increase its viscosity
Explanation
Tetraethyllead (TEL), not tetramethyl lead, was historically added to petrol (gasoline) as an anti-knock agent to prevent engine knocking in internal combustion engines. Knocking occurs when the air-fuel mixture in the engine cylinder ignites prematurely or unevenly, causing inefficient combustion and potential engine damage. TEL reduces knocking by raising the octane rating of petrol, allowing it to resist premature ignition under high compression ratios.
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Organic chemistry begins with carbon compounds classified by carbon skeleton, saturation and functional group. Work includes identifying groups such as hydroxyl, carbonyl, carboxyl and amino, applying basic nomenclature, and distinguishing structural, geometric and optical isomers, where the same molecular formula does not necessarily mean the same structure or properties.
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