UPSC Prelims 2024 · GS Paper I
Question 3: Geography
Consider the following :
- 1.Pyroclastic debris
- 2.Ash and dust
- 3.Nitrogen compounds
- 4.Sulphur compounds
How many of the above are products of volcanic eruptions ?
AnswerUPSC’s answer is (d).
Volcanoes throw out solids, liquids and gases. The solids include pyroclastic debris (bombs, lapilli) and ash and dust; the gases and liquids include nitrogen compounds and sulphur compounds, with smaller amounts of chlorine, hydrogen, ammonia and argon. So all four items are products of eruptions. Remember the NCERT list: lava, pyroclastic debris, ash and dust, and gases such as nitrogen and sulphur compounds.
- 1. Pyroclastic debris is fragmented solid material thrown out by an eruption.
- 2. Ash and dust are fine solid eruption products.
- 3. Nitrogen compounds are among the gases released.
- 4. Sulphur compounds such as sulphur dioxide are major volcanic gases.
How you could have got this
No shortcut here: in a “how many” question, ruling out options doesn’t help. Every statement has to be judged.
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) Wrong: far more than one item is a volcanic product.
- (b) Wrong: all four, not two, are volcanic products.
- (c) Wrong: nitrogen and sulphur compounds are volcanic emissions too, so three is short by one.
- (d) Right: pyroclastic debris, ash and dust, nitrogen compounds and sulphur compounds all come from eruptions.
Answer: UPSC’s key. Explanation: written by UPSC Grade, not by UPSC.
Source: UPSC, Civil Services (Preliminary) Examination 2024, General Studies Paper I, Series A. The paper on upsc.gov.in.