UPSC Prelims 2004 · General Studies
Question 56: Science and Technology
Consider the following statements:
- 1.Banking soda is used in fire extinguishers.
- 2.Quicklime is used in the manufacture of glass.
- 3.Gypsum is used in the manufacture of Plaster of Paris.
Which of the statements given above is/are correct?
AnswerThe answer is (d).
All three statements are accepted as correct. Baking soda (sodium bicarbonate) releases carbon dioxide on contact with acid and is used in soda-acid fire extinguishers. Lime (quicklime, with limestone) is one of the raw materials of glass, alongside sand and soda ash. Gypsum, heated gently, loses water to give Plaster of Paris.
- 1. Baking soda is used in fire extinguishers.
- 2. Lime is used in making glass.
- 3. Gypsum is heated to make Plaster of Paris.
How you could have got this
- If you were sure statement 1 is correct, (b) goes: it leaves 1 out.
What you needed to know: Baking soda is used in fire extinguishers.
- Then, if you were sure statement 3 is correct, (a) and (c) go: each of them leaves 3 out.
What you needed to know: Gypsum is heated to make Plaster of Paris.
Only (d) is left. You didn’t need statement 2.
This follows an unofficial answer: UPSC has not published its key for this year, and if that answer is wrong, so is this path.
Which options go is worked out from UPSC’s key and the options, not by a model.
Why each option is right or wrong
- (a) Leaves out statement 3, which is also correct.
- (b) Leaves out statement 1, which is also correct.
- (c) Leaves out statements 2 and 3, which are also correct.
- (d) Correct: all three statements hold.
Explanation: written by UPSC Grade, not by UPSC.
Source: UPSC, Civil Services (Preliminary) Examination 2004, General Studies. UPSC's own paper isn't online; the words are from a published compilation. The paper on upsc.gov.in.