UPSC Prelims 2005 Q16: Science & Technology – Chemistry
Consider the following statements :
1. Anhydrous sodium carbonate is commonly known as baking soda
2. Baking soda is used in fire extinguishers
3. Bleaching powder is manufactured in Hasenclever plant
Which of the statements given above is/are correct?
- (a) 1, 2 and 3
- (b) 2 and 3
- (c) 3 only
- (d) 1 and 2
Answer: (b) 2 and 3
Explanation
Sodium carbonate, baking soda and bleaching powder
| Statement | Verdict |
|---|---|
| 1. Anhydrous sodium carbonate is baking soda | False: it is soda ash; baking soda is sodium bicarbonate |
| 2. Baking soda is used in fire extinguishers | True — it releases CO2 with acid |
| 3. Bleaching powder is made in Hasenclever plant | True — Hasenclever plant makes bleaching powder |
Statements 2 and 3 are correct.
Answer: (b) 2 and 3.
Why each option is right or wrong
- (a) Incorrect. Statement 1 is false.
- (b) CORRECT. Statements 2 and 3 are correct.
- (c) Incorrect. Statement 2 is also correct.
- (d) Incorrect. Statement 1 is false.
Key point
Washing soda: Na2CO3·10H2O. Soda ash: Na2CO3. Baking soda: NaHCO3.
Remember
Baking soda (NaHCO3) is used in soda-acid fire extinguishers.
Common mistakes
- Calling soda ash by the name baking soda.
- Forgetting that baking soda is sodium bicarbonate.
- Not recalling the Hasenclever plant for bleaching powder.
Exam tip
Bleaching powder: Ca(OCl)Cl made by chlorine on slaked lime in a Hasenclever plant.
Sources
- NCERT Class X Science — Acids, Bases and Salts
- NCERT Class XI Chemistry — The s-Block Elements (sodium carbonate and sodium hydrogencarbonate)