UGC NTA NET/JRF Exam, Environmental Sciences, June-2021

Total Questions: 100

41. Among all the unbiased estimators of the population regression coefficients which are linear in the dependent variable (say Yᵢ), the least squares estimators have the smallest variance. This statement is known as:

Correct Answer: D. Gauss-Markov theorem
Solution:



42. The place of origin of the National River Ganga is:

Correct Answer: C. Gomukh
Solution:

The Ganges River originates in the Himalaya Mountains at Gomukh, the terminus of the Gongotri Glacier. When the ice of this glacier melts, it forms the clear waters of the Bhagirathi River.

As the Bhagirathi River flows down the Himalayas, it joins the Alaknanda River, officially forming the Ganges River.

43. Water remains in liquid state over a wide range of temperature because of its:

(a) Specific heat
(b) Heat of vapourisation
(c) Density at 0°C
(d) Bipolar nature
Choose the most appropriate answer from the options given below:

Correct Answer: C. (a) and (b) Only
Solution:

Water has strong hydrogen bonds between molecules. These bonds require a lot of energy before they will break. This leads to water having a higher boiling point than if there were only weaker dipole-dipole forces. Water also has a high specific heat.

44. The difference in values of theoretical oxygen demand and actual oxygen demand is observed because of:

(a) difference in rate of reaeration and deoxуgenation
(b) addition of dead cell biomass of bacteria as waste
(c) accumulation of waste in bacterial tissue
(d) formation of humus which resists degradation
Choose the most appropriate answer from the options given below:

Correct Answer: B. (b) and (d) Only

45. The crystal structure of a compound/material can be determined using:

(a) Scanning Electron Microscoре
(b) X-Ray Fluorescence
(c) Transmission Electron Microscopy
(d) X-Ray Diffraction
Choose the most appropriate answer from the options given below: 

Correct Answer: D. (c) and (d) Only

46. Which of the following are living fossils?

(a) Ginkgo biloba
(b) Panthera tigris
(c) Elephas Maximas
(d) Latimavia
Choose the most appropriate answer from the options given below:

Correct Answer: A. (a) and (d) Only
Solution:

Ginkgo biloba is the world's oldest living plant, and is known as a 'living fossil' because it has no close living relatives. It is found in fossils dating back 270 million years.

47. Consider the following statements:

(a) Earth is farthest from the sun at the time of perehelion
(b) When perihelion occurs, it is winter season in the northern hemisphere
(c) Seasons on earth occur due to inclination in earth's axis of rotation
Choose the most appropriate answer from the options given below:

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

Perihelion currently occurs around 3 January each year. This is in the northern hemisphere Winter. The seasons are mainly due to the obliquity of the Earth's axis of rotation, or axial tilt.

At perihelion the Earth is about 147,000,000 km from the Sun. Earth's tilted axis causes the seasons. Throughout the year, different parts of Earth receive the Sun's most direct rays.

So, when the North Pole tilts toward the Sun, it's summer in the Northern Hemisphere. And when the South Pole tilts toward the Sun, it's winter in the Northern Hemisphere.

48. Ferromagnesian minerals are:

(a) a group of silicates
(b) black, brown or green colour minerals
(c) a group of bicarbonates
(d) highly resistant to weathering and erosional process
Choose the most appropriate answer from the options given below:

Correct Answer: C. (a) and (b) Only
Solution:

Ferromagnesian Minerals: Silicate minerals in which cations of iron and magnesium form essential chemical components. The term is used to cover such minerals as the olivines, pyroxenes, amphiboles, and the micas biotite and phlogopite.

Single chain Pyroxene is another family of dark ferromagnesian minerals, typically black or dark green in colour. Members of the pyroxene family have a complex chemical composition that includes iron, magnesium, aluminum, and other elements bonded to polymerized silica tetrahedra.

49. Consider the following statements regarding clay minerals in soil:

(a) Some clay particles are technically not colloids yet they have colloid like properties
(b) There are four major types of colloids present in soil
(c) All types of clays are crystalline in nature
(d) Soil humus are not considered as colloids
Choose the most appropriate answer from the options given below: 

Correct Answer: C. (a) and (b) Only
Solution:

Soil colloids can be defined as the particle of soil with a diameter less than 1 µm. Soil is composed of a mixture of solids, liquids, and gases phases. The solid fragment of soils comprises an inorganic and organic material. There are four major types of colloids present in soil

  • Layer silicate clays
  • Iron and aluminum oxide clays (sesquioxide clays)
  • Allophane and associated amorphous clays
  • Humus.

50. Consider the following statements:

(a) Richter magnitude is based upon the amplitude of the largest seismic wave produced during an earthquake
(b) An earthquake with Richter magnitude 7 produces 10 times larger displacement on the seismogram than does a magnitude 6
(c) S-waves travel faster than P waves through solid materials
Choose the most appropriate answer from the options given below:

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

The first widely-used method, the Richter scale, was developed by Charles F. Richter in 1934.

It used a formula based on the amplitude of the largest wave recorded on a specific type of seismometer and the distance between the earthquake and the seismometer.

The Richter scale is a base-10 logarithmic scale, meaning that each order of magnitude is 10 times more intensive than the last one. In other words, a two is 10 times more intense than a one and a three is 100 times greater.

In the case of the Richter scale, the increase is in wave amplitude. That is, the wave amplitude in a level 6 earthquake is 10 times greater than in a level 5 earthquake, and the amplitude increases 100 times between a level 7 earthquake and a level 9 earthquake. The amount of energy released increases 31.7 times between whole number values.