Question

Assertion (A): When the pH of rainwater drops below 5.6, it is called acid rain.

Reason (R): Acid rain is formed when oxides of carbon dissolve in rainwater.

Options

• If both A and R are true, and R is the correct explanation of A.

• If both A and R are true, and R is the correct explanation of A.

• If A is true, but R is false.

• If both A and R are false.

Answer 1

If both A and R are true, and R is the correct explanation of A.

Explanation:

The assertion is true because rainwater with a pH value dropping below 5.6 is officially classified as acid rain. The reason is also technically true because oxides of carbon (like CO₂) dissolve in normal rainwater to form weak carbonic acid, giving unpolluted rain its naturally lower baseline pH of 5.6. However, R is not the correct explanation for A because the drastic drop below 5.6 that creates harmful acid rain is primarily driven by stronger industrial pollutants, specifically oxides of sulfur (SO₂) and nitrogen (NO_x), which form sulfuric and nitric acids.