691: In an objective test there are 60 questions. Each question carries four alternative answers only one of which is correct. Suppose A and B are two candidates both of whom know correct answers to 30 questions. A answers only 30 questions while B answers all 60 questions choosing answers at random for those he does not know the answers of. If each question carries a mark of 1 and no negative marks are awarded, the marks obtained by B are expected to be larger than those obtained by A by
(a) 0
(b) 15
(c) 5
(d) 7.5
692: Humidity of the air:
(a) Increases with the increase in atmospheric temperature
(b) Decreases with the increase in atmospheric temperature
(c) Is not affected by the change in atmospheric temperature
(d) Does not show any consistent behaviour with the change in atmospheric temperature
693: In the context of proposals to the use of hydrogen-enriched CNG (H-CNG) as fuel for buses in public transport, consider the following statements:
1. The main advantage of the use of H-CNG is the elimination of carbon monoxide emissions.
2. H-CNG as fuel reduces carbon dioxide and hydrocarbon emissions.
3. Hydrogen up to one-fifth by volume can be blended with CNG as fuel for buses.
4. H-CNG makes the fuel less expensive than CNG.
Which of the statements given above is/are correct?
(a) 1 only
(b) 2 and 3 only
(c) 4 only
(d) 1, 2, 3 and 4
694: Which of the following is the most important cause for the decline of Buddhism after Ashoka ?
(a) Non patronage by the kings
(b) Condemnation of animal sacrifices
(c) Growth of licentious practices in Buddhist centres
(d) Allegiance to the middle path
695: What can be the impact of excessive / inappropriate use of nitrogenous fertilizers in agriculture?
1. Proliferation of nitrogen-fixing microorganisms in soil can occur.
2. Increase in the acidity of soil can take place.
3. Leaching of nitrate to the ground-water can occur.
Select the correct answer using the code given below.
(a) 1 and 3 only
(b) 2 only
(c) 2 and 3 only
(d) 1, 2 and 3