1. Which of the following statements is not correct?
(a) The velocity of sound in air decreases as the humidity increases.
(b) The velocity of sound in air is independent of pressure.
(c) The velocity of sound in air increases with the increase in temperature.
(d) The velocity of sound in air is not affected by the change in amplitude and frequency
2. In the context of physics, the phenomenon of “Reverberation” refers to:
(a) The collection of reflected sounds from the surfaces of any enclosure.
(b) The sensation of sound persists in our brain.
(c) The reflection back of ultrasonic waves after hitting any obstacle.
(d) None of these.
Answer: (a) Explanation: A sound created in a big hall will persist by repeated reflection from the walls until it is reduced to a value where it is no longer audible. The repeated reflection that results in this persistence of sound is called reverberation. Thus, reverberation is the collection of reflected sounds from the surfaces in an enclosure like an auditorium. It is a desirable property of auditoriums to the extent that it helps to overcome the inverse square law drop-off of sound intensity in the enclosure (I=P/4πr2). Hence, option (a) is correct. Additional Info: In an auditorium or big hall, excessive reverberation is highly undesirable. To reduce reverberation, the roof and walls of the auditorium are generally covered with sound- absorbent materials like compressed fibreboard, rough plaster or draperies.
3. Consider the following statements about 'Project Tiger':
(1) It was launched in 1973 to ensure conservation of Tiger population in India.
(2) State governments on their own can de-notify a tiger reserve.
(3) The limit of buffer zone is determined on the basis of scientific and objective criteria in consultation with the concerned Gram Sabha and an Expert Committee.
Which of the statements given above is/are correct?
(a) 1 only
(b) 2 only
(c) 3 only
(d) 1 and 3 only
Answer: (d) Explanation: Statement (1) is correct. The Government of India took a pioneering initiative for conserving its national animal, the tiger, by launching the ‘Project Tiger’ in 1973 with the following objectives:
➢ To ensure maintenance of available population of Tigers in India for scientific, economic, aesthetic, cultural and ecological value.
➢ To preserve, for all times, the areas of such biological importance as a national
heritage for the benefit, education and enjoyment of the people. Statement (2) is incorrect. No State government shall de-notify a tiger reserve, except in public interest with the approval of the National Tiger Conservation Authority (NTCA) and the approval of the National Board for Wild Life (NBW). Statement (3) is correct. The project aims at promoting co-existence between wildlife and human activity with due recognition of the livelihood, developmental social and cultural rights of the people. The limit of buffer zone is determined on the basis of scientific and objective criteria in consultation with the concerned Gram Sabha and an Expert Committee constituted for the purpose.
4. Consider the following pairs:
Disease : Microorganisms
1. Malaria : Protozoa
2. Athlete’s foot : Fungi
3. Typhoid : Bacteria
4. Chicken pox : Virus
Which of the pair(s) given above is/are correctly matched?
(a) 1 and 3 only
(b) 1 and 4 only
(c) 1, 2 and 3 only
(d) 1, 2, 3 and 4
Answer: (d) Explanation: Diseases caused by Protozoa: Dysentery and malaria Diseases caused by Fungi: Athlete’s foot Diseases caused by Bacteria: Typhoid and tuberculosis Diseases caused by Virus: Polio and Chicken Pox.
5. Dengue is a fever caused and spread by which of the following?
(a) Virus and female Aedes Mosquito
(b) Bacteria and female Culex mosquito
(c) Fungi and female Aedes mosquito
(d) Protozoan and female Anopheles mosquito
Answer: (a) Explanation: Dengue fever is a mosquito-borne tropical disease caused by the dengue virus. Dengue is spread by several species of mosquito of the Aedes type, principally female A. aegypti.