Acids, Bases and Salts — Chemistry STD 10 — Question
ICSE BoardEnglish MediumSTD 10ChemistryAcids, Bases and Salts1 Mark
MCQ
Rain is called acid rain when its:
A
pH falls below 7
B
pH falls below 6
✓
pH falls below 5.6
D
pH is above 7
✓
Answer
Correct option: C.
pH falls below 5.6
(c) pH falls below 5.6 Explanation : With a pH range of 5-6, natural rainwater becomes mildly acidic. It becomes acid rain when the pH level of rainwater falls below this range. Thus, acid rain typically has a pH lower than 5.6 , indicating increased acidity due to the presence of acidic pollutants like sulphur dioxide $\left( SO _2\right)$ and nitrogen oxides $NOx$ in the atmosphere.
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