Q66 / 180 · AIIMS 2015 · Chemistry

Assertion: Change in colour of acidic solution of potassium dichromate by breath is used to test drunken drivers. Reason : Change in colour is due to complexation of alcohol with potassium dichromate.

  • A
    If both assertion and reason are true and reason is the correct explanation of assertion.
  • B
    Ifboth assertion and reason are true but reason is not the correct explanation of assertion.
  • Correct answer
    C
    If assertion is true but reason is false.
  • D
    If both assertion and reason are false.

Solution

Acidified $\mathrm{K}_2 \mathrm{Cr}_2 \mathrm{O}_7$ (orange in colour) solution oxidises alcohol and itself gets reduced to $\mathrm{Cr}_2\left(\mathrm{SO}_4\right)_3$ which is green in colour.

Hence, the correct answer is option: 'C'.

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