UPSC Prelims 2003 Q108: Science & Technology – Chemistry
Assertion (A): Unsaturated fats are more reactive compared with the saturated fats.
Reason (R): Unsaturated fats have only single bonds in their structure.
- (a) Both A and R are individually true and R is the correct explanation of A
- (b) Both A and R are individually true but R is NOT the correct explanation of A
- (c) A is true but R is false
- (d) A is false but R is true
Answer: (c) A is true but R is false
Explanation
Unsaturated and saturated fats
| Part | Verdict |
|---|---|
| A. Unsaturated fats are more reactive than saturated fats | True |
| R. Unsaturated fats have only single bonds | False: they have double (or triple) bonds |
A is true and R is false: unsaturated fats contain double bonds, which make them more reactive.
Answer: (c) A is true but R is false.
Why each option is right or wrong
- (a) Incorrect. R is false, so it cannot explain A.
- (b) Incorrect. R is not a true statement.
- (c) CORRECT. A is true because of the double bonds, but R wrongly says only single bonds.
- (d) Incorrect. A is true, as double bonds make them reactive.
Key point
Unsaturated: C=C bonds, liquid oils; saturated: single bonds, solid fats.
Remember
Unsaturated fats have double bonds and are more reactive.
Common mistakes
- Thinking unsaturated fats have only single bonds.
- Mixing up saturated with unsaturated reactivity.
- Forgetting the hydrogenation of vegetable oils.
Exam tip
Hydrogenation converts unsaturated oils into saturated fats.
Sources
- NCERT Class XI Chemistry — Hydrocarbons (alkenes: unsaturation)
- Encyclopaedia Britannica — lipid