Question

Which air pollutant is mainly responsible for acid rain?

• A. CO and CO$_2$
• B. NO$_2$ and SO$_2$
• C. O$_3$ and PAN
• D. NH$_3$ and CH$_4$

Hint:

Acid rain is always linked with {SO$_2$ and NO$_x$}. Remember: sulphuric and nitric acids are the culprits.

Answer 1

The Correct Option is B

Step 1: Understanding acid rain.
Acid rain refers to precipitation such as rain, snow, or fog that contains strong acidic components. These acids are mainly sulfuric acid (H$_2$SO$_4$) and nitric acid (HNO$_3$), which are formed due to chemical reactions of certain air pollutants in the atmosphere.
Step 2: Formation mechanism of acid rain.
Sulphur dioxide (SO$_2$) and nitrogen dioxide (NO$_2$) are released into the atmosphere from burning fossil fuels, industrial processes, and vehicle emissions. These gases react with oxygen, water vapor, and oxidizing agents in the atmosphere to form sulfuric acid and nitric acid.
Step 3: Analysis of options.
(A) CO and CO$_2$: Carbon monoxide is toxic, and carbon dioxide causes global warming, but neither directly forms strong acids responsible for acid rain.
(B) NO$_2$ and SO$_2$: Correct — These gases are the primary precursors of nitric acid and sulfuric acid, which cause acid rain.
(C) O$_3$ and PAN: These are components of photochemical smog, not acid rain.
(D) NH$_3$ and CH$_4$: Ammonia can neutralize acids, and methane is mainly a greenhouse gas.
Step 4: Final conclusion.
Since sulphur dioxide and nitrogen dioxide directly form strong acids in the atmosphere, the correct answer is (B) NO$_2$ and SO$_2$.