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

Total Questions: 100

71. What is the correct order of abundance of following heavy metals in the earth's crust?

(a) Fe
(b) Mg
(c) Al
(d) Cu
Choose the correct answer from the options given below:

Correct Answer: C. (c) > (a) > (b) > (d)
Solution:
Heavy Metals NameHeavy Metals SymbolAbundance in the Earth’s Crust (ppm)
IronFe56,300
MagnesiumMg23,300
AluminiumAl82,300
CopperCu60

72. Identify the correct sequence in ascending order of the grade of metamorphism

(a) Gneiss
(b) Slate
(c) Schist
(d) Shale
Choose the correct answer from the options given below:

Correct Answer: D. (d), (b), (c), (a)
Solution:
Rock TypeGrade of Metamorphism
GneissHigh Grade
SchistMedium Grade
SlateLow Grade
ShaleVery Low Grade

73. In the context of urban environment, arrange the following in order of increasing residence time.

(a) Formaldehyde
(b) Carbon monoxide
(c) Peroxyacetyl nitrate
(d) Hydroxyl radical
Choose the correct answer from the options given below: 

Correct Answer: C. (d) < (a) < (c) < (b)
Solution:
CompoundResidence Time
Formaldehyde0.1 and 1.2 days
Carbon monoxide0.3 and 5.0 years
Peroxyacetyl nitrateUpto 7 days
Hydroxyl radical10⁻⁹ seconds

74. Identify the correct sequence of Life Time (years) of the green house gases in increasing order:

(a) CH₄ (Methane)
(b) N₂O (Nitrous Oxide)
(c) CFC-12
(d) O₃ (Tropospheric)
Choose the correct answer from the options given below:

Correct Answer: B. (d), (a), (c), (b)
Solution:
Green House GasesLife Time (years)
CH₄12 to 15 years
N₂O (Nitrous Oxide)114 years
CFC-12113 years
O₃ (Tropospheric)23 days

75. Identify the correct sequence of Net Heating Value (MJ/Kg) in increasing order for the following fuels.

(a) Charcoal
(b) Bituminous coal
(c) Regular gasoline
(d) Natural gas
(e) Oak wood
Choose the correct answer from the options given below:

Correct Answer: D. (e), (a), (b), (c), (d)
Solution:
FuelsNet Heating Value (MJ/kg)
Charcoal28 MJ/kg
Bituminous coal22,000 MJ/kg
Regular gasoline49,000,000 MJ/kg
Natural gas50,000,000 MJ/kg
Oak wood18.5 to 19 MJ/kg

76. Identify the correct sequence of conversion of a fertile nuclear material to a fissile material involving the following nuclei:

Choose the correct answer from the options given below:

Correct Answer: D. (d), (b), (a), (c)

77. Identify the correct sequence of moisture content (%) in ascending order in the following categories of wastes:

(a) Animal solids and organic waste
(b) Trash
(c) Rubbish
(d) Garbage
(e) Refuse
Choose the correct answer from the options given below:

Correct Answer: D. (b), (c), (e), (d), (a)

78. According to the Solid Waste Management Rules 2016, arrange the following metals in decreasing order of their permissible concentration (mg/kg) in the prepared compost:

(a) Chromium
(b) Lead
(c) Cadmium
(d) Copper
Choose the correct answer from the options given below:

Correct Answer: C. (d), (b), (a), (c)
Solution:
MetalsPermissible Concentration (mg/kg)
Chromium0.24 to 6.3 mg/kg
Lead10 mg/kg
Cadmium0.1 mg/kg
Copper50 mg/kg

79. Given below are two statements:

Statement I: Mean deviation is a better measure of dispersion than the quartile deviation.

Statement II: Mean deviation is obtained by dividing the algebraic sum of deviations about mean by total number of observations.
In the light of the above statements, choose the correct answer from the options given below:

Correct Answer: C. Statement I is true, but Statement II is false
Solution:

The mean deviation is defined as a statistical measure that is used to calculate the average deviation from the mean value of the given data set.

The mean deviation of the data values can be easily calculated using the below procedure.

• Step 1: Find the mean value for the given data values
• Step 2: Now, subtract the mean value from each of the data values given (Note: Ignore the minus symbol)
• Step 3: Now, find the mean of those values obtained in step 2.

Mean Deviation is the mean of all the absolute deviations of a set of data, whereas Quartile deviation is the difference between "first and third quartiles" in any distribution. Thus. Mean deviation is a better measure of dispersion than the quartile deviation.

80. Given below are two statements:

Statement I: The log-normal distribution is positively skewed.
Statement II: A negatively skewed distribution has its long tail to the left.

In the light of the above statements, choose the correct answer from the options given below:

Correct Answer: A. Both Statement I and Statement II are true
Solution:

If one tail is longer than another, the distribution is skewed. These distributions are sometimes called asymmetric or asymmetrical distributions as they don't show any kind of symmetry.

Symmetry means that one half of the distribution is a mirror image of the other half. For example, the normal distribution is a symmetric distribution with no skew. The tails are exactly the same.

A left-skewed distribution has a long-left tail. Left-skewed distributions are also called negatively-skewed distributions. That's because there is a long tail in the negative direction on the number line.

The mean is also to the left of the peak. Log-normal distributions are positively skewed with long right tails due to low mean values and high variances in the random variables.