Which one of the following is a cause of acid rains ?

Acid rain is primarily caused by the emission of sulfur dioxide (SO2) and nitrogen oxides (NOx) into the atmosphere [2]. These gases are released largely through the combustion of fossil fuels in power plants, industrial processes, and motor vehicles [3]. Once in the atmosphere, sulfur dioxide reacts with water, oxygen, and other chemicals to undergo oxidation, forming sulfuric acid (H2SO4) [4]. Similarly, nitrogen oxides form nitric acid (HNO3) [2]. These acids mix with atmospheric moisture and precipitate as rain, snow, or fog with a pH typically lower than 5.6 [4]. While ozone acts as a photo-oxidant that can stimulate these reactions, and ammonia can react with acids to form salts, sulfur dioxide remains a direct primary precursor and a major cause of the acidification process [6]. Carbon monoxide, though a pollutant, does not contribute to acid rain formation [5].

Sources

1. [1] Environment, Shankar IAS Acedemy .(ed 10th) > Chapter 5: Environmental Pollution > 5.15.4. Chemistry of Acid Rain > p. 103
2. [2] Environment and Ecology, Majid Hussain (Access publishing 3rd ed.) > Chapter 6: Environmental Degradation and Management > Acidification > p. 8
3. [3] Physical Geography by PMF IAS, Manjunath Thamminidi, PMF IAS (1st ed.) > Chapter 6: Geomorphic Movements > Anthropogenic Solution Weathering > p. 91
4. [4] Environment, Shankar IAS Acedemy .(ed 10th) > Chapter 5: Environmental Pollution > 5.I5. ACID RAIN > p. 101
5. [6] https://eplanning.blm.gov/public_projects/lup/63197/78289/88520/Appendix04_Air_Quality_Tech_Support.pdf
6. [5] https://www.epa.gov/sites/default/files/2017-11/documents/trends_brochure_2006.pdf