31. Which of the following groups of gases contribute to the ‘Green House Effect’?
(a) Ammonia and Ozone
(b) Carbon mono-oxide and Sulphur dioxide
(c) Carbon tetrafluoride and Nitrous oxide
(d) Carbon dioxide and Methane
Ans: (d)
[The most abundant greenhouse gases in Earth’s atmosphere are: Water vapour (H2O), Carbon dioxide (CO2 ), Methane (CH4 ), Nitrous oxide (N2O), Ozone (O3 ) and CFCs.]
32. Which one of the following is the correct definition of “ Agenda 21”?
(a) It is an action plan of the U.N.O for protecting human rights.
(b) It is a book with 21 chapters on nuclear disarmament.
(c) It is an action plan for sustainable development.
(d) It is an agenda for the election of the president in the next meeting of SAARC
Ans: (c)
[Agenda 21 is a non-binding, voluntarily implemented action plan of the United Nations with regard to sustainable development. It is a product of the UN Conference on Environment and Development (UNCED) held in Rio de Janeiro, Brazil, in 1992. The “21” in Agenda 21 refers to the 21st Century.]
33. Deep black soil is productive due to the high proportion of
(a) sand and zinc
(b) gravel and calcium
(c) clay and humus
(d) silt and earthworm.
Ans:(c)
[Deep black soil is productive due to the high proportion of clay and humus. The organic matter present in the soil is contributed by the death and decay of living organisms. These are the richest in nutrients and therefore these soils are the most fertile.]
34. Pick up the correct food chain
(a) grass – chameleon – insect – bird
(b) grass – fox – rabbit – bird
(c) phytoplankton – zooplankton – fish
(d) fallen leaves – bacteria – insect larvae.
Ans:(c)
[The process of transfer of energy from producers through a series of organisms, i.e., from primary consumers to secondary consumers and from secondary consumers to tertiary consumers by the process of eating and being eaten is known as a food chain. The correct food chain is phytoplankton – zooplankton – fish.]
35. Consider the following statements:
I. ECG is a test that measures the electrical activity of the heart.
II. ECG is not used to measure the rate and regularity of heartbeats.
Which of the statement/s given above is/are correct?
(a) I only
(b) II only
(c) Both I and II
(d) None of these
Ans:(a)
[ECG is a test that measures the electrical activity of the heart. ECG is used to measure the rate and regularity of heartbeats.]
36. Which of the following diseases are infectious in milch animals?
I. Hand diseases
II. Anthrax
III. Black quarter
IV. Cowpox
Select the correct answer from the codes given below:
(a) I, II and III
(b) II, III and IV
(c) I and IV
(d) I, II, III and IV
Ans: (b)
[Milch animals are those animals that are sources of milk, e.g. cow, goat, and buffalo. Foot-and-mouth disease, caused by Aphthae epizootic is an infectious disease that affects cloven-hoofed animals. Anthrax is an acute infectious disease caused by the bacterium Bacillus anthracis.]
37. Consider the following statement about lymph
I. Lymph is another medium of circulation in the human body.
II. Lymph flows in only one direction – from the heart to body tissues.
IV. Lymph protects the body by killing the germs drained out of the body tissues with the help of Lymphocytes.
Codes:
(a) I and III are correct
(b) I and II are correct
(c) II and III are correct
(d) I, II and III are correct
Ans: (a)
38. When a person, after a certain degree of exertion, suffers from pain in the chest or below the collar bones, in the event of inadequate supply of oxygen to the heart muscles, he is said to suffer from
(a) coronary thrombosis
(b) myocardial infarction
(c) angina pectoris
(d) arteriosclerosis
Ans:(c)
[Angina pectoris is the medical term for chest pain or discomfort due to coronary heart disease. It occurs when the heart muscle doesn’t get as much blood as it needs. Angina usually causes uncomfortable pressure, fullness, squeezing or pain in the centre of the chest.]
39. Consider the following statements:
I. A historic bronze statue of the Father of the Nation Mahatma Gandhi was unveiled at the Parliament of the USA.
II. The statue has been crafted by British sculptor Philip Jackson.
Which of the statements given above is/are correct?
(a) I only
(b) II only
(c) Both I and II
(d) None of the above
Ans: (b)
[A historic bronze statue of Mahatma Gandhi was unveiled at Parliament Square in London.]
40. H2O is liquid and H2S is gas because
(a) oxygen forms a stronger hydrogen level than sulphur.
(b) oxygen is less electronegative than sulphur.
(c) the atomic radius of oxygen is less than that of sulphur.
(d) the atomic radius of oxygen is greater than that of sulphur.
Ans: (a)
[H2O has intermolecular hydrogen bonds between its molecules (H—O—H H—O—H) while H2S has weak Van der Waals forces between its molecules. Hence the molecules of H2O are more strongly packed than H2S, thus water is in a liquid state at room temperature.]
