UPSC Prelims 2006 Q19: Science & Technology – Materials & Engineering
Assertion (A): Cellulose is used in making shatter - proof glass.
Reason (R): Polysaccharides are not soluble in water.
- (a) Both A and R are true and R is the correct explanation of A
- (b) Both A and R are true but R is not a correct explanation of A
- (c) A is true but R is false
- (d) A is false but R is true
Answer: (a) Both A and R are true and R is the correct explanation of A
Explanation
Cellulose and shatter-proof glass
| Part | Evaluation |
|---|---|
| Assertion (A): Cellulose is used in making shatter-proof glass | True: cellulose derivatives (e.g. cellulose acetate or nitrate) form the tough plastic interlayer in laminated safety glass |
| Reason (R): Polysaccharides are not soluble in water | True: cellulose is a polysaccharide that is insoluble in water |
| Link | Water-insolubility keeps the cellulose layer stable and unaffected by moisture, which is why it is suitable as a durable binder |
Both statements are true and R supports A, as the accepted key states.
Answer: (a) Both A and R are true and R is the correct explanation of A.
Why each option is right or wrong
- (a) CORRECT. Cellulose derivatives are used in shatter-proof glass and its water-insolubility makes the layer stable.
- (b) Incorrect. The accepted key treats R as the explanation for A, not merely a true statement.
- (c) Incorrect. R is true: polysaccharides like cellulose are insoluble in water.
- (d) Incorrect. A is true; cellulose derivatives are used in laminated safety glass.
Key point
Cellulose derivatives form the tough interlayer in shatter-proof glass, and the water-insolubility of this polysaccharide keeps the layer stable.
Remember
Cellulose is used in shatter-proof glass; polysaccharides are water-insoluble.
Common mistakes
- Thinking cellulose is only used in paper and cloth.
- Assuming all polysaccharides dissolve like sugars.
- Missing the link between stability in moisture and the glass application.
Exam tip
Safety glass has a plastic (cellulose or polyvinyl) layer between glass sheets that holds fragments together.
Sources
- NCERT Class XII Chemistry — Biomolecules (carbohydrates: polysaccharides)
- NCERT Class XII Chemistry — Polymers (cellulose acetate)