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State PCS PYQPrelims 2025

BPSC – Combined Competitive Examination · Question 137

Which compound has been used to increase the octane rating of petrol?

  1. Trimethylhexane
  2. Tetramethyl oxide
  3. Tetraethyl lead
  4. Triethyl toluene
Show answer & explanation

Answer: (C) Tetraethyl lead

Explanation

Tetraethyl lead (TEL) reduces engine knocking and raises octane number; it has been phased out due to lead pollution.

  • (A) Incorrect

    Wrong: not the classic anti-knock additive.

  • (B) Incorrect

    Wrong: not a standard additive.

  • (C) Correct

    Correct: TEL was the classic anti-knock agent (now phased out for health reasons).

  • (D) Incorrect

    Wrong: not a standard additive.