Question

During acid rains, the pH of rainwater is approximately ___.

• A. 7
• B. 6.5
• C. 6
• D. 5.6

Answer 1

The correct option is D

5.6

Acid rain is a term referring to precipitation (rain, snow, sleet, fog, cloud water, dew etc.) mixed with acidic components. Water has a neutral pH of 7. Liquids with a pH less than 7 are acidic, and those with a pH greater than 7 are alkaline. Unpolluted rain has an acidic pH, but usually no lower than 5.7, because carbon dioxide and water in the air react together to form carbonic acid, which is a weak acid. Similarly, the presence of pollutants such as oxides of sulphur and nitrogen results in the formation of sulphurous acid and nitrous acid which are also weak acids.