Question 1: Why does rain water have a pH of about 5 – 6?
Solution: Normally rain has a pH of about 5 – 6 due to dissolution of of the atmosphere into it.
Question 2: Explain giving reasons. ‘The presence of CO reduces the amount of haemoglobin available in the blood for carrying oxygen to the body cells’.
Solution: CO combines with haemoglobin of the red blood corpuscles about 300 times more easily than oxygen to form carboxy haemoglobin reversibly as follows:
Thus it is not able to combine with oxygen to form oxyhaemoglobin and transport of oxygen to different body cell cannot take place.
Question 3: Why is acid rain considered as a threat to ‘Taj Mahal’?
Solution: Taj Mahal is made of marble. The acid rain contains which attacks the marble thereby pitting it, decolourising it and making it lustreless.
Question 4: The acid rain does not contain
(a) Sulphuric acid
(b) Nitric acid
(c) Sulphurous acid
(d) Acetic acid
Solution: Nitrogen oxides & acidic soots. Sulphurdioxide & nitrogen dioxide interact with water vapours in presence of sunlight to form sulphuric acid & nitric acid units.
Acid rain contains sulphuric acid, nitric acid, sulphurous acid but does not contain acetic acid.
Hence, the correct option is D.