CBSE Class 10 Science 2020 · Paper 31(B) · Question 3
Answer question numbers 3(a) – 3(d) on the basis of your understanding of the following paragraph and the related studied concepts.
Taj Mahal, the great wonder of the world, is made of white marble which is composed of calcium carbonate.
About 60 years ago it was discovered that this monument is being eaten away by acid rain. The Archaeological Survey of India, that looks after this building of historical importance is of the opinion that the atmospheric pollution due to vehicular traffic and industries, mainly Mathura Refinery may be a major cause of acid rain in and around the monument. Normal rain is slightly acidic because it absorbs some from the atmospheric air. Acid rain is more acidic than normal rain because it also has absorbed oxides of nitrogen and sulphur.
- (a)Write the chemical formula of calcium carbonate.[1]
- (b)List two gases that are the main contributors of acid rain.[1]
- (b)OR : Name the gas that is liberated when acid rain falls on calcium carbonate.[1]
- (c)Rain is called acid rain when its pH value is (A) 3 (B) 5.5 (C) 7.8 (D) 9.7[1]
- (d)Select the correct statement about calcium : (A) It is a metal and its valency is one. (B) Its electronic configuration is (2, 8, 8, 2). (C) It is a non-metal with valency two. (D) It is more reactive than sodium and potassium.[1]
Answer
Calcium carbonate is ; acid rain comes from sulphur and nitrogen oxides; its pH is below 5.6; calcium is .
(a) .
(b) Sulphur dioxide () and nitrogen dioxide (), the oxides of sulphur and nitrogen given out by vehicles and industries.
OR (b) Carbon dioxide (): .
(c) Options (A) and (B): and . Normal rain has a pH of about , and rain is called acid rain when its pH falls below this value; both values are below it.
(d) Option (B): Its electronic configuration is .
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