What can be the impact of excessive/inappropriate use of nitrogenous fertilizers in agriculture?1.Proliferation of nitrogen-fixing microorganisms in soil can occur.2.Increase in the acidity of soil can take place.3.Leaching of nitrate to the ground water can occur.Select the correct answer using the codes given below

1. A

   1 and 3 only

   (a) 1 and 3 only. Nitrate leaching (3) is real, but statement 1 is the wrong way round: surplus mineral nitrogen typically suppresses, not proliferates, symbiotic nitrogen-fixers. Including 1 knocks this option out.

2. B

   2 only

   (b) 2 only. Acidification from ammonium/urea fertilisers is correct, but leaching of nitrate is also a standard impact. 2 only is incomplete.

3. C

   2 and 3 only

   (c) 2 and 3 only. Excess nitrogenous fertiliser can acidify soil and send nitrate into groundwater. It does not cause a bloom of nitrogen-fixing microbes. Statements 2 and 3 are the valid pair and the official key.

4. D

   1, 2 and 3

   (d) 1, 2 and 3. Statement 1 is incorrect, so the full set cannot be the key.

Summary. Official key is (c) 2 and 3 only. Overuse of nitrogenous fertilisers can raise soil acidity and leach nitrate to groundwater. Nitrogen-fixers are not encouraged by a nitrate glut; they are often outcompeted. Statement 1 is therefore false. The keyed pair is acidification plus leaching.