Environmental Chemistry - Result Question 20
20. The $pH$ of rain water, is approximately
(2019 Main, 9 Jan II)
(a) 7.5
(b) 6.5
(c) 5.6
(d) 7.0
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Answer:
Correct Answer: 20. (c)
Solution:
- In clean air, rain water picks up some acidic oxides like $CO _2$ and $SO _2$ (obtained from volcanic eruptions). These substance make the rain slightly acidic $(pH=5.6-6)$.