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

Total Questions: 100

11. Match the celebration of days related to environment with their corresponding dates:

List-I (Days)List-II (Dates)
(a) Earth Day(i) 2nd February
(b) International Ozone Day(ii) 16th September
(c) International Biodiversity Day(iii) 22nd April
(d) Wetland Day(iv) 22nd May

Choose the correct answer from the options given below:

(a)(b)(c)(d)
A(ii)(iii)(i)(iv)
B(iv)(ii)(iii)(i)
C(iii)(ii)(i)(iv)
D(iii)(ii)(iv)(i)
Correct Answer: D.
Solution:

(a) Earth Day is an annual event celebrated around the world on April 22 to demonstrate support for environmental protection. First celebrated in 1970, it now includes events coordinated globally by the Earth Day Network in more than 193 countries.
(b) September 16 was designated by the United Nations General Assembly as the International Day for the Preservation of the Ozone Layer. This designation had been made on December 19, 2000, in commemoration of the date, in 1987, on which nations signed the Montreal Protocol on Substances that Deplete the Ozone Layer.
(c) The International Day for Biological Diversity is a United Nations-sanctioned international day for the promotion of biodiversity issues. It is currently held on May 22. The International Day for Biological Diversity falls within the scope of the UN Post-2015 Development Agenda's Sustainable Development Goals.
(d) World Wetlands Day occurs annually on February 2, marking the date of the adoption of the Convention on Wetlands on February 2, 1971 when a small group of environmentalists signed an international agreement at the Ramsar Convention in Iran.

12. Match the following iron oxides with their chemical formulae:

List-I (Iron Oxides)List-II (Chemical Formulae)
(a) Haematite(i) FeO. TiO₂
(b) Magnetite(ii) Fe₃O₄
(c) Ilmenite(iii) FeO. H₂O
(d) Limonite(iv) Fe₂O₃

Choose the correct answer from the options given below:

(a)(b)(c)(d)
A.(iv)(ii)(iii)(i)
B.(ii)(iv)(i)(iii)
C.(ii)(iv)(iii)(i)
D.(iv)(ii)(i)(iii)
Correct Answer: D.
Solution:

(a) Hematite, also spelled as haematite, is a common iron oxide with a formula of FeO and is widespread in rocks and soils. Hematite forms in the shape of crystals through the rhombohedral lattice system, and it has the same crystal structure as ilmenite and corundum..
(b) Magnetite is a rock mineral and one of the main iron ores, with the chemical formula Fe O4. It is one of the oxides of iron, and is ferrimagnetic; it is attracted to a magnet and can be magnetized to become a permanent magnet itself. It is the most magnetic of all the naturallyoccurring minerals on Earth.
(c) Ilmenite, also known as manaccanite, is a titanium-iron oxide mineral with the idealized formula FeTiO3. It is a weakly magnetic black or steel-gray solid. From a commercial perspective, ilmenite is the most important ore of titanium. Ilmenite is the main source of titanium dioxide, which is used in paints, printing ink, fabrics, plastics, paper, sunscreen, food and cosmetics.
(d) Limonite is an iron ore consisting of a mixture of hydrated iron(III) оoxidehydroxides in varying composition. The generic formula is frequently written as FeO(OH) nH,O. Limonite is one of the three principal iron ores, the others being hematite and magnetite, and has been mined for the production of iron since at least 2500 ВСЕ.

13. Mean marks of 200 students in statistics are 47. The mean marks of top 25% students are 72 and that of bottom 25% students are 25. Which of the following are the mean marks of the remaining students?

Correct Answer: C. 45.5
Solution:

14. Assuming the incoming solar radiation to be 100 units. Consider the following statements about the radiation budget of earth:

(a) About 51 units of solar radiation are absorbed by earth's surface.
(b) About 20 units of long-wave radiation emitted from earth's surface are lost to space directly without being absorbed by the atmosphere.
(c) About 19 units of solar radiation are absorbed by the atmosphere.
Which of the above statements are correct?

Correct Answer: C. (a) and (c) only
Solution:

About 30% (30 units) of the incident solar radiation is reflected back tot space. Two thirds of the reflected radiation, i.e., 20 units is reflected by clouds, 4 units are reflected by earth surface and the remaining 6 units are reflected by the atmosphere. Out of the remaining 70 units of the incident solar radiation, 19 units are absorbed by the atmosphere and clouds, while the remaining 51 units are absorbed at the earth surface. Out of 19 units of incident solar radiation absorbed during the passage through the atmosphere, 16 units are absorbed in cloudfree air by water vapour, ozone and dust particles, while 3 units are absorbed by clouds.
The earth loses the 51 units of solar radiation, which it has absorbed through 21 units of net emission of long-wave infrared radiation from the earth surface (i.e., upward emission of long-wave infrared radiation from the earth surface minus the downward emission of longwave infrared radiation from the atmosphere to the surface), 23 units of latent heat flux through melting and evaporation of water and 7 units of sensible heat flux through conduction and convection processes.

15. Consider the following statements regarding sampling:

(a) The sample mean is an unbiased estimate of the population mean.
(b) For small samples, the sample variance is an unbiased estimate of the population variance.
(c) If we reject the null hypothesis when it is actually true, we commit the type-I error in testing the hypothesis.
Which of the above statements are correct?

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

The sample mean is a random variable that is an estimator of the population mean. The expected value of the sample mean is equal to the population mean μ. Therefore, the sample mean is an unbiased estimator of the population mean.
The investigator establishes the maximum chance of making type I and type II errors in advance of the study. The probability of committing a type I error (rejecting the null hypothesis when it is actually true) is called a (alpha) the other name for this is the level of statistical significance. If a study of Tamiflu and psychosis is designed with a = 0.05, for example, then the investigator has set 5% as the maximum chance of incorrectly rejecting the null hypothesis. The probability of making a type II error (failing to reject the null hypothesis when it is actually false) is called ẞ (beta). The quantity (1- ẞ) is called power, the probability of observing an effect in the sample (if one), of a specified effect size or greater exists in the population.

16. Consider the following statements regarding Poisson Distribution:

(a) It is a continuous probability distribution.
(b) It is applicable when 'n' the number of trials is indefinitely large and 'p' the probability of success is indefinitely small.
(c) Its mean is equal to its variance.
Which of the above statements are correct?

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

The Poisson distribution can also be used for the number of events in other specified intervals such as distance, area or volume. The Poisson distribution is popular for modeling the number of times an event occurs in an interval of time or space. The Poisson distribution can be applied to systems with a large number of possible events, each of which is rare. The number of such events that occur during a fixed time interval is, under the right circumstances, a random number with a Poisson distribution.
In Poisson Distribution mean is equal to its variance.

17. Match the following discontinuities with the boundaries they are found at:

List-I (Discontinuities)List-II (Boundaries Between)
(a) Mohorovicic discontinuity(i) Lower mantle and outer core
(b) Conrad discontinuity(ii) Hydrosphere and crust
(c) Lehman discontinuity(iii) Lower crust and upper mantle
(d) Gutenberg discontinuity(iv) Outer core and inner core

Choose the correct answer from the options given below:

(a)(b)(c)(d)
A.(iii)(ii)(iv)(i)
B.(i)(iii)(ii)(iv)
C.(iii)(ii)(i)(iv)
D.(iv)(iii)(ii)(i)
Correct Answer: A.
Solution:

Earth's interior is made of different kinds of materials. Each of those materials are different from each other by their physical and chemical properties, such as temperature, density etc. Unique layers are there according to their characteristics inside the earth. All those layers are separated from each other through a transition zone. These transition zones are called discontinuities.
There are five discontinuities inside the earth.
Conrad Discontinuity: Transition zone between SIAL and SIMA.
Mohorovicic Discontinuity: Transition zone between the Crust and Mantle.
Repiti Discontinuity: Transition zone between Outer mantle and Inner mantle.
Gutenberg Discontinuity: Transition zone between Mantle and Core.
Lehman Discontinuity: Transition zone between Outer core and Inner core.

18. In an objective type examination, there are 100 questions. One mark is awarded for each correct answer and 0.125 marks are deducted for each incorrect answer. The number of marks scored by the students in this examination is an example of which of the following types of variables?

Correct Answer: A. Discrete
Solution:

Variables that can only take on a finite number of values are called "discrete variables." All qualitative variables are discrete. Some quantitative variables are discrete, such as performance rated as 1, 2, 3, 4, or 5, or temperature rounded to the nearest degree. In an objective type examination, there are 100 questions.
One mark is awarded for each correct answer and 0.125 marks are deducted for each incorrect answer. The number of marks scored by the students in this examination is an example of discrete types of variables.

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

Assertion (A): Isostacy is the corresponding state of balance between extensive blocks of earth's crust which rise to different levels and appear at the surface as mountains, plateaus, plains or ocean floor.
Reason (R) : There is a certain minimum depth below sea level where the pressure due to the weight of overlying material in each unit column is everywhere the same.
In the light of above two statements, choose the correct options.

Correct Answer: B. Both (A) and (R) are true, but (R) is not the correct explanation of (A).
Solution:

For the ideal condition of gravitational equilibrium that controls the heights of continents and ocean floors, in accordance with the densities of their underlying rocks, the term isostasy. Isostasy is the corresponding state of balance between extensive blocks of the Earth's crust which rise to different levels and appear at the surface as mountain ranges, plateaus, plains or ocean floors. The idea implies that there is a certain minimum depth below sea-level where the pressure due to the weight of the overlying material in each unit column is everywhere the same. In figure this level of uniform pressure is that of the base of the highest block.
Fig. Wooden blocks of different heights floating in water (shown in front as a section through the tank), to illustrate the concept of isostatic balance between adjacent columns of the Earth's crust.

20. Match the following commonly used separation equipments with their separates:

List-I (Equipment)List-II (Separate)
(a) Electromagnetic Separator(i) Heavy and light fraction
(b) Trommel Screen(ii) Non-ferrous metals
(c) Air Classifier(iii) Ferrous Metals
(d) Eddy Current Separator(iv) Particulates

Choose the correct answer from the options given below:

(a)(b)(c)(d)
A(i)(ii)(iv)(iii)
B(iii)(iv)(i)(ii)
C(ii)(iv)(iii)(i)
D(iii)(i)(iv)(ii)
Correct Answer: B.
Solution:

(a) Electromagnetic separators are simple in design and operation. They extract ferrous metals from the wastestream by means of magnetic attraction. Configurations can vary from overhead to under the conveyor belt. Overhead electromagnets pulls waste up out of the wastestream as it travels underneath on the conveyor belt.
(b) The trommel screen system consisted of a cylindrical separation device that rotated to perform size separation.
(c) Air classifiers are sometimes used in MSW processing systems for separating components of low density and high air resistance, called the light fraction, from components of high density and low air resistance, called the heavy fraction. The light fraction consists largely of paper. cloth, and cardboard, but it also contains light plastics. The heavy fraction consists of metal, glass, stones and heavy plastics.
(d) An eddy current separator uses a powerful magnetic field to separate non-ferrous metals from waste after all ferrous metals have been removed previously by some arrangement of magnets. The device makes use of eddy currents to effect the separation. Eddy current separators are not designed to sort ferrous metals which become hot inside the eddy current field. This can lead to damage of the eddy current separator unit belt.