UGC-NET (NTA) Environmental Sciences, December-2019

Total Questions: 100

61. Identify the INCORRECT statement about organophosphate pesticides from the following statements:

Correct Answer: D. They decompose and metabolize slowly.
Solution:

Organo Phosphates: They are not persistent, but are more acutely toxic to humans than the organo chlorines that they have replaced. They are rapidly absorbed through the skin, lungs, and gastrointestinal tract. The exposed humans have shown a range of symptoms such as tremor, confusion, slurred speech, muscle twitching (jerking) and convulsions. Organo phosphates such as parathion, malathion, diazinon, tetraethyl prophosphate (TEPP), and diamethoate are effective against wide range of insects.

62. Strike-slip faults are examples of plate movement which is:

Correct Answer: B. parallel to the strike of the fault plane
Solution:

A strike-slip fault is present where the movement of blocks bounding the fault is parallel to the strike of the fault. A right-slip, right strike-slip, or right-lateral fault is a strikeslip fault along which strike-slip or strikeseparation movement on the side or block of the fault opposite the observer has moved right (strike slip) or seemingly to the right (strike separation).

63. Consider the following statements about the Lotka-Volterra Model:

(a) Both the populations of prey and predator oscillate sinusoidically
(b) There is a phase difference of π/2 between the prey and predator populations
(c) Populations of prey and predator are directly proportional to each other
(d) Population of prey and predator are inversely proportional to each other
Which of the above statements are correct?

Correct Answer: A. (a) and (b) only
Solution:

We can use them to draw several conclusions about the cyclic variation of the predator and prey on such trajectories.
1. The sizes of the predator and prey populations vary sinusoidally with period 2π/√ac. This period of oscillation is independent of the initial conditions.
2. The predator and prey populations are out of phase by one-quarter of a cycle. The prey leads and the predator lags.
3. The amplitudes of the oscillations are Kc/y for the prey and √acK/a for the predator and hence depend on the initial conditions as well as on the parameters of the problem.
4. The average populations of predator and prey over one complete cycle are c/y and a/a, respectively.

64. The landscape used by wild animals for their movement between forest patches, is called:

Correct Answer: A. Wildlife Corridor
Solution:

Wildlife movement corridors, also called dispersal corridors or landscape linkages as opposed to linear habitats, 1 are linear features whose primary wildlife function is to connect at least two significant habitat areas (Beier and Loe 1992). These corridors may help to reduce or moderate some of the adverse effects of habitat fragmentation by facilitating dispersal of individuals between substantive patches of remaining habitat, allowing for both long-term genetic interchange and individuals to re-colonize habitat patches from which populations have been locally extirpated.

65. Given below are two statements, one is labelled as Assertion (A) and the other is labelled as Reason (R).

Assertion (A): Aluminium Chloride is a good coagulant for treatment of raw water.
Reason (R): Both the colloidal particles and Aluminium ions are positively charged.
In the light of above two statements, choose the correct options.

Correct Answer: C. (A) is true, but (R) is false.
Solution:

Alum is widely used as a coagulant in most of the water treatment plants in spite of its limitations on the temperature, turbidity, pH. Inorganic polyvalent Aluminium salt has been used as a coagulant for treatment of water worldwide. When dose to raw water, inorganic coagulants decrease its alkalinity.

66. Which one among the following is the correct order of steps taken during the process of Environmental Impact Assessment (EIA)?

Correct Answer: C. Screening, Scoping, EIA, Public Hearing, Issue of Environmental Clearance
Solution:

The environmental impact assessment in India was started in 1976-77 when the Planning Commission asked the then Department of Science and Technology to examine the rivervalley projects from environmental angle. The EIA Cycle and Procedures: The EIA process in India is made up of the following phases:
1. Screening
2. Scoping and consideration of alternatives
3. Baseline data collection
4. Impact prediction
5. Assessment of alternatives
6. Delineation of mitigation measures
7. Environmental impact statement
8. Public hearing
9. Environmental management plan
10. Decision making
11. Monitoring and clearance conditions.

67. Consider the following changes with regard to dissolution of ammonia in water:

(a) increase in temperature
(b) decrease in pH of the solution
(c) increase in partial pressure of ammonia
The solubility of ammonia would increase by which of the above changes?

Correct Answer: C. (b) and (c) only

68. Consider the following gases:

(a) CO               (b) CH₄
(c) HCFCs          (d) CO₂            (e) SO₃
Those gases removed from the atmosphere by the process of oxidation are:

Correct Answer: B. (a), (b) and (c) only
Solution:

The atmosphere is an oxidizing medium. Many environmentally important trace gases are removed from the atmosphere mainly by oxidation: greenhouse gases such as CH₄ toxic combustion gases such as CO, agents for stratospheric O₃ depletion such as HCFCs, and others.
It is thought that oxidation of species emitted from the Earth's surface, such as CO and CH₄ required transport to the stratosphere followed by reaction with OH in the stratosphere: CO + OH → CO₂ + H (R4)
CH₄+ OH→→ CH₃ + H₂O (R5).

69. When a stable layer exists below the stack height and an unstable layer above, which of the following types of plume behaviour is expected to be observed?

Correct Answer: D. Lofting
Solution:

Lofting Plume: Under conditions of strong super adiabatic lapse rate just above the stack and negative lapse rate (inversion) just below the opening of stack, lofting plume is obtained.
The upward mixing of plume is very rapid and turbulent, but downward mixing is less because the downward movement is prevented by inversion.
The dispersion of pollutants therefore becomes rapid and pollutants cannot come down to the ground. Such kind of a plume is ideal for dispersion of air pollutants and protection of living beings to a great extent.

70. Which of the following statements is NOT correct with regard to chemical analysis by flame photometer?

Correct Answer: D. When ion returns from excited state to ground state, it absorbs the radiation of a characteristic frequency.
Solution:

Flame photometry is a method used for the determination of elements which can be easily excited, for example, alkali and alkaline earth metals. This method is based upon the measurement of intensity of radiation emitted, in the visible region, when a metal atom is introduced into a flame. The wavelength of the radiation (or the colour), emitted tells us what the element is, and the intensity of the radiation tells us how much of the element is present.