AIIMS2006Chemistryd and f Block Elements
Assertion : Change in colour of acidic solution of potassium dichromate by breath is used to test drunk drivers. Reason : Change in colour is due to the complexation of alcohol with potassium dichromate.
Options
- AIf both assertion and reason are true and reason is the correct explanation of the assertion
- BIf both assertion and reason are true but reason is not the correct explanation of the assertion
- CIf assertion is true, but reason is false
- DBoth assertion and reason are false statements.
Correct answer
C. If assertion is true, but reason is false
Step-by-step solution
Change in colour is due to the oxidation of alcohol with potassium dichromate. Oxidation of alcohols with K ₂ Cr ₂ O ₇ in dilute H ₂ SO ₄ (orange solution): K ₂ Cr ₂ O ₇ in presence of dilute H ₂ SO ₄ acts as an oxidising agent. It is converted into chromic sulphate which is green in colour. gathered K ₂ Cr ₂ O ₇+4 H ₂ SO ₄ K ₂ SO ₄+ Cr ₂ ( SO ₄ )₃+4 H ₂ O + 3 2 O ₂ (orange) gathered (green)