UPSC Prelims 2019 · GS Paper I
Question 41: Environment and Ecology
Consider the following statements :
- 1.Agricultural soils release nitrogen oxides into environment.
- 2.Cattle release ammonia into environment.
- 3.Poultry industry releases reactive nitrogen compounds into environment.
Which of the statements given above is/are correct?
AnswerUPSC’s answer is (d).
All three statements are correct. Fertilised agricultural soils release nitrogen oxides, including nitrous oxide, through microbial nitrification and denitrification. Cattle dung and urine release ammonia, and poultry droppings also give off ammonia and other reactive nitrogen compounds. Agriculture and livestock are the main sources of ammonia emissions, and reactive nitrogen adds to air and water pollution.
- 1. Fertilised soils emit nitrogen oxides.
- 2. Cattle waste releases ammonia.
- 3. Poultry waste releases ammonia and other reactive nitrogen.
How you could have got this
- If you were sure statement 1 is correct, (b) and (c) go: each of them leaves 1 out.
What you needed to know: Fertilised soils emit nitrogen oxides.
- Then, if you were sure statement 2 is correct, (a) goes: it leaves 2 out.
What you needed to know: Cattle waste releases ammonia.
Only (d) is left. You didn’t need statement 3.
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) Cattle also release ammonia, so statement 2 is correct too.
- (b) Agricultural soils also release nitrogen oxides.
- (c) Soils and poultry also release reactive nitrogen.
- (d) Correct: all three are sources of reactive nitrogen.
Answer: UPSC’s key. Explanation: written by UPSC Grade, not by UPSC.
Source: UPSC, Civil Services (Preliminary) Examination 2019, General Studies Paper I, Series A. The paper on upsc.gov.in.