UGC NTA NET/JRF Exam, Environmental Sciences, June-2025

Total Questions: 99

71. Arrange the following geological/paleoclimate events from oldest to youngest:

A. Setting up of Monsoon climate on the Indian subcontinent
B. Appearance of Homo Sapiens
C. Appearance of free oxygen on the earth
D. Last Glacial Maximum
E. Deposition of Gondwana coals
Choose the correct answer from the options given below:

1. C, E, A, B, D
2. E, C, D, A, B
3. D, C. E. В, A
4. D, C, А, B. E

Correct Answer: 1. C, E, A, B, D

Solution:

72. Consider the following statements about solubility of gases in surface water.

A. Equilibrium concentration of a dissolved gas in water as per Henry's law is referred to as its saturation value.
B. There may be more dissolved gas in water than its saturation value in water.
C. It is more common for a dissolved gas to be present in less amount in water than its saturation value in water.
D. The excess or deficit of a dissolved gas compared to its saturation value cannot be brought back to saturation level in water.
E. Solubility of gas depends on partial pressure of the gas but is independent of purity of water.
Choose the correct answer from the options given below:

1. A, B, C and E only
2. A, B and C only
3. А, B, C and D only
4. A, C, D and E only

Correct Answer: 2. A, B and C only

Solution:

73. Which of the following process in gassification of waste is endothermic?

1. C + O₂ → CO₂
2. C + H₂O → СO + H₂
3. C + 2H₂ → CH
4. 2C + O₂→ 2CO

Correct Answer: 2. C + H₂O → СO + H₂

Solution:

74. Consider the following statements and Choose the INCORRECT statement:

1. Ozone partially absorbs UV-B in stratosphere
2. Conversion of inactive to active chlorine occur at surface of particles formed by solution of H₂O, H₂SO₄, and HNO₃
3. Bromine containing hydrogen free substances 'Halons' do not have ozone depleting potential
4. Denitrification of lower stratosphere extends life of the Antarctic ozone hole

Correct Answer: 3. Bromine containing hydrogen free substances 'Halons' do not have ozone depleting potential

Solution:

75. Choose the CORRECT statements:

A. Thermosetting plastic is easier to recycle compared to thermoplastic.
B. Microplastic include plastic size less than 5 µm only.
C. Thermal depolymerisation involves the conversion of assorted polymers into petroleum.
D. Incineration is not an environment friendly option to dispose plastic waste.
E. Recycled PET can be used effectively for making variety of fabrics.
Choose the correct answer from the options given below:

1. А, C and E only
2. C, D and E only
3. B, C, D and E only
4. A, D and E only

Correct Answer: 2. C, D and E only

Solution:

76. Choose the INCORRECT statement:

1. Components of air quality standards are the indicator, an averaging time, the form and the level.
2. Primary air quality standards are more restrictive than the secondary.
3. Primary and Secondary air quality standards are periodically reviewed every year.
4. Agriculture operations and urban centers are examples of distributed sources of air pollution.

Correct Answer: 3. Primary and Secondary air quality standards are periodically reviewed every year.

Solution:

Incorrect: "Primary and Secondary air quality standards are periodically reviewed every year." Reviews are not annual (e.g., NAAQS reviews are typically on multi-year cycles ~5 years). Why the others are correct:

1. Standards specify the indicator (pollutant), averaging time, form (e.g., percentile, exceedances), and level (concentration).

2. Primary standards protect public health and are at least as strict as secondary (welfare) standards; saying "more restrictive" is generally true in intent, though some pollutants have equal primary/secondary levels.

4. Agriculture operations and urban areas act as distributed (area) sources rather than single point sources.

77. Which of the following are likely consequences of global climate change?

A. It will increase acidity of oceans.
B. Labile pool of C in soils will mobilise much faster.
C. It may accelerate soil salinization.
D. It exacerbated the incidence of coral bleaching.
E. Argonite will be more likely to dissolve into seawater.
Choose the correct answer from the options given below:

1. A. D and E only
2. A, B and D only
3. A, В, C and D only
4. A, B, С, D and E

Correct Answer: 4. A, B, С, D and E

Solution:

A. Ocean acidity increases: More CO2 dissolving → carbonic acid → lower pH.

B. Labile soil C mobilizes faster: Warming accelerates microbial respiration and turnover.

C. Soil salinization may accelerate: Higher evapotranspiration, sea-level rise/intrusion, and altered recharge exacerbate salt build-up.

D. Coral bleaching worsens: Warmer seas and acidification stress corals, increasing bleaching events.

E. Aragonite more likely to dissolve: Acidification reduces aragonite saturation, promoting dissolution.

78. Which of the following was NOT a cause of dispersed radioactivity during nuclear power plant accident in Chernobyl, Ukraine in the year 1985?

1. ¹³¹Xe and ⁸⁵K
2. ¹³¹I
3. ²³⁹Pu
4. ¹³⁴Cs and ¹³⁷Cs

Correct Answer: 3. ²³⁹Pu

Solution:

79. Consider the following statements about analysis on analytical instruments and data quality.

A. Minimum detection limit (MDL) is three time of σₙ₋₁ of blank concentration.
B. Minimum quantification limit (MQL) is 7-10 times of σₙ₋₁ of blank concentration.
C. Lower concentration limit of a working linear range must be greater than the defined MDL.
D. Relative standard deviation is used as a measure of precision of the data.
E. An analytical data with high precision may or may not be accurate.
Choose the correct answer from the options given below: