State PCS PYQPrelims 2024

BPSC – Combined Competitive Examination · Question 40

Which of the following are the constituents of a soda-acid fire extinguisher?

  1. Conc. sulphuric acid and aluminium sulphate
  2. Dil. sulphuric acid and sodium carbonate
  3. Dil. sulphuric acid and sodium bicarbonate solution
  4. Conc. sulphuric acid and sodium carbonate solution
Show answer & explanation

Answer: (C) Dil. sulphuric acid and sodium bicarbonate solution

Explanation

In a soda-acid extinguisher, H₂SO₄ reacts with NaHCO₃ solution to produce CO₂ under pressure.

  • (A) Incorrect

    Wrong: aluminium sulphate is used in foam extinguishers.

  • (B) Incorrect

    Wrong: sodium bicarbonate, not carbonate, is used.

  • (C) Correct

    Correct: they react to release CO₂ that smothers the fire.

  • (D) Incorrect

    Wrong: wrong base and acid strength.