Identify correct statements regarding pollution.
(A) In air pollution, carbon monoxide and hydro-carbon pollution is involved.
(B) In urban environment the pH value of the first rain after summer is always lower than the subsequent rains.
(C) Smog is caused by air pollution.
(D) Smog is caused by water pollution.
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → (A), (B) and (C) only
(A) In air pollution, carbon monoxide and hydro-carbon pollution is involved. Correct. The table of pollution types lists, for air pollution, oxides of sulphur and nitrogen, carbon monoxide, hydro-carbon, ammonia, lead and other substances, coming from the burning of coal, petrol and diesel and from industry.
(B) In urban environment the pH value of the first rain after summer is always lower than the subsequent rains. Correct. Air pollution can cause acid rain. Through the dry summer, oxides of sulphur and nitrogen from burning fuel collect in the city air; the first rain washes them down, so it is the most acidic and its pH is lower than that of the rains that follow through cleaner air.
(C) Smog is caused by air pollution. Correct. Smoke and gases from vehicles and industry mix with the fog over cities, and this smoky fog, called urban smog, is caused by atmospheric pollution. Breathed in, it is very harmful to health.
(D) Smog is caused by water pollution. Incorrect. Smog hangs in the air; water pollution spoils rivers and lakes, not the air.
NCERT (2025-26): “Air Pollution … Smoky fog over cities called as urban smog is caused by atmospheric pollution. It proves very harmful to human health. Air pollution can also cause acid rains. Rainwater analysis of urban environment has indicated that pH value of the first rain after summer is always lower than the subsequent rains.…”
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