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State PCS PYQPrelims 2022

BPSC – Combined Competitive Examination · Question 100

Consider the following statements: 1. Dissolving salt in pure water raises its boiling point and lowers its freezing point. 2. Adding methyl alcohol to water lowers the boiling point of water. Which of the above is/are correct?

  1. 1 only
  2. 2 only
  3. Both 1 and 2
  4. Salt and methyl alcohol behave the same way
  5. None of the above / More than one of the above
Show answer & explanation

Answer: (C) Both 1 and 2

Explanation

Non-volatile solutes raise boiling point (colligative property); a more volatile liquid like methanol lowers it.

  • (A) Incorrect

    Wrong: statement 2 is also correct.

  • (B) Incorrect

    Wrong: statement 1 is also correct.

  • (C) Correct

    Correct: salt (non-volatile) elevates BP and depresses FP; volatile methanol lowers the mixture's BP.

  • (D) Incorrect

    Wrong: they have opposite effects on boiling point.

  • (E) Incorrect

    Wrong: only one of the options A–D is correct.