Question

Which of the following statements are true?

I. Sulphur dioxide reacts with atmospheric water vapour to form sulphur trioxide

II. Acid mixed with atmospheric water vapour can precipitate only in the form of rain

III. Acid rain has detrimental effects on both plant and animal life

• A. I and III
• B. II and III
• C. Only II
• D. Only III

Answer 1

The correct option is D Only III

Acid rain refers to any form of precipitation which contains acidic components, such as sulfuric acid or nitric acid and falls to the ground in wet (rain, fog, snow) or dry (acidic gases and chemicals blown by wind) forms.

When pollutants such as oxides of nitrogen and sulphur dioxide (SO2) are added in large concentrations to the air, they react with oxygen, atmospheric water vapour and other chemicals to form acids such as nitric acid and sulphuric acid. These acids mix with rain water or other substances before they fall on to the ground in wet or dry forms.

Sulphur dioxide (SO2) reacts with atmospheric water vapour (H2O) to form sulphurous acid (H2SO3) but not sulphur trioxide.

Sulphur trioxide (SO3) is formed when sulphur dioxide reacts with oxygen.

Thus, statements I and II are incorrect.

Acid rain alters the pH of soil and water bodies. This negatively affects the growth of plants and kills aquatic organisms. It also causes damage to assets and properties by spoiling or corroding structures made up of stone, marble, limestone, etc.

Thus, statement III is correct.