Acid rain

Factories, power plants and vehicles release these gases. In clouds they dissolve in water droplets and form sulphuric acid and nitric acid. The rain can fall far from where the gases came from. Its harm includes:

• Damage to leaves and forests.
• Lakes and soil turn acidic, which harms fish and crops.
• Nutrients are washed out of the soil.
• Marble monuments wear away, and metal bridges corrode.

The syllabus names ways to cut these gases, such as using CNG or unleaded petrol in vehicles.

A small example

Marble is calcium carbonate. Acid in the rain reacts with it. So a marble statue left in the open slowly loses its fine detail.

Where marks go

The 2024 and 2025 ICSE Biology papers each asked for two harmful effects of acid rain, for 2 marks. The marking scheme took any two specific effects. CISCE's report on the 2025 ICSE Biology paper names "pollution" and "harms plants" as vague answers. It gives "corrosion of monuments" and "leaching of nutrients" as the kind of specific effect wanted.

So each effect should name what is harmed and how. "It corrodes marble monuments" says both. "It is bad for nature" says neither.

About the author

Deepti Sardana

Founder Member & Academic Lead

An IIT alumna (M.Sc., M.Phil.) with over 25 years in teaching, child psychology and learning assessment. As Academic Lead at EduBrahma, she leads the method TRUtesting uses to find where and why a child loses marks.

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