Back to Sections

Type:ALLMCQNATMSQ

Atmospheric Processes and Air Quality Parameters(14)Particulate Pollutants: Measurement and Control(7)Air Quality Management and Dispersion Modelling(7)Noise Pollution(3)

Atmospheric Processes and Air Quality Parameters

14 Questions

GATE→2026→Air and Noise Pollution→Atmospheric Processes and Air Quality Parameters

Q1

MCQ[1 Mark]

The general atmospheric composition of gases in the decreasing order is

(A)

$N_2 > O_2 > CO > CO_2 > NH_3$

(B)

$N_2 > O_2 > CO_2 > CO > NH_3$

(C)

$N_2 > CO_2 > O_2 > NH_3 > CO$

(D)

$N_2 > CO_2 > NH_3 > CO > O_2$

Explanation

GATE→2026→Air and Noise Pollution→Atmospheric Processes and Air Quality Parameters

Q2

MCQ[2 Marks]

Which ONE of the following options CORRECTLY matches the Criteria Air Pollutants with measurement methods used in Continuous Ambient Air Quality Stations (CAAQMS) operated by Central Pollution Control Board (CPCB) given in the table?

(A)

(P) - (i); (Q) - (ii); (R) - (iii); (S) - (iv)

(B)

(P) - (iv); (Q) - (iii); (R) - (ii); (S) - (i)

(C)

(P) - (iii); (Q) - (i); (R) - (iv); (S) - (ii)

(D)

(P) - (ii); (Q) - (iii); (R) - (i); (S) - (iv)

Explanation

GATE→2026→Air and Noise Pollution→Atmospheric Processes and Air Quality Parameters

Q3

NAT[2 Marks]

Standard deviation for the particulate matter (PM) concentrations listed in the table is _____ $\mu\text{g/m}^3$ (rounded off to one decimal place). Locations (1 to 7): 65, 45, 55, 60, 40, 50, 35

Explanation

GATE→2026→Air and Noise Pollution→Atmospheric Processes and Air Quality Parameters

Q4

NAT[2 Marks]

The mixing ratio of $CO_2$ at a pressure of 1 atm and at 300K is reported as 340 ppmv. Considering ideal gas conditions, the equivalent concentration of $CO_2$ in air is _____ $\text{mg/m}^3$ (rounded off to two decimal places). (Molecular weight of $CO_2 = 44\text{ g/mol}$; Universal gas constant $= 8.314\text{ J/mol-K}$; $1\text{ atm} = 101325\text{ Pa}$)

Explanation

GATE→2026→Air and Noise Pollution→Atmospheric Processes and Air Quality Parameters

Q5

NAT[2 Marks]

In a stack emission measurement at an industry, the stack cross-sectional area at 30 m height was divided into four equal sectors. The measured velocities and $SO_2$ concentrations through these sectors at this height are given in the table. The mean $SO_2$ concentration from the stack is _____ $\text{mg/m}^3$ (rounded off to two decimal places). Sector 1: $v = 15\text{ m/s}$, $C = 1000\text{ mg/m}^3$ Sector 2: $v = 17\text{ m/s}$, $C = 1150\text{ mg/m}^3$ Sector 3: $v = 19\text{ m/s}$, $C = 1250\text{ mg/m}^3$ Sector 4: $v = 21\text{ m/s}$, $C = 1275\text{ mg/m}^3$

Explanation

GATE→2024→Air and Noise Pollution→Atmospheric Processes and Air Quality Parameters

Q6

MSQ[1 Mark]

Which is/are the secondary air pollutant(s)?

(A)

$O_3$

(B)

$HNO_3$

(C)

$CO_2$

(D)

$H_2SO_4$

Explanation

GATE→2024→Air and Noise Pollution→Atmospheric Processes and Air Quality Parameters

Q7

NAT[2 Marks]

The concentration of Ozone ($O_3$) corresponding to a mixing ratio of $120\text{ ppbv}$ at pressure of $1\text{ atm}$ and temperature of $25^\circ\text{C}$ is _____ $\mu\text{g/m}^3$ (rounded off to 1 decimal place). (Atomic weight of oxygen = $16$, $R = 8.314\text{ J/K-mol}$)

Explanation

GATE→2023→Air and Noise Pollution→Atmospheric Processes and Air Quality Parameters

Q8

MCQ[1 Mark]

Which of the following is true according to the Central Pollution Control Board (CPCB), Government of India's notification issued in the year 2009?

(A)

24 hour averaged standard for $PM_{2.5}$ in ambient air is $60\text{ }\mu\text{g/m}^3$; 24 hour averaged standard for $PM_{10}$ in ambient air is $100\text{ }\mu\text{g/m}^3$

(B)

24 hour averaged standard for $PM_{2.5}$ in indoor air is $60\text{ }\mu\text{g/m}^3$; 24 hour averaged standard for $PM_{10}$ in ambient air is $100\text{ }\mu\text{g/m}^3$

(C)

24 hour averaged standard for $PM_{2.5}$ in ambient air is $60\text{ }\mu\text{g/m}^3$; 24 hour averaged standard for $PM_{10}$ in indoor air is $100\text{ }\mu\text{g/m}^3$

(D)

24 hour averaged standard for $PM_{2.5}$ in indoor air is $60\text{ }\mu\text{g/m}^3$; 24 hour averaged standard for $PM_{10}$ in indoor air is $100\text{ }\mu\text{g/m}^3$

Explanation

GATE→2023→Air and Noise Pollution→Atmospheric Processes and Air Quality Parameters

Q9

MCQ[1 Mark]

The sub index values of $NO_2$, $SO_2$ and $PM_{10}$ are 80, 80 and 100, respectively. According to the National Air Quality Index (NAQI) released by the Government of India in the year 2015, the overall NAQI is

(A)

80

(B)

260

(C)

100

(D)

151

Explanation

GATE→2023→Air and Noise Pollution→Atmospheric Processes and Air Quality Parameters

Q10

MCQ[2 Marks]

Match the following: - J) Dalton's law -> (ii) Pressure exerted by a mixture of gases - K) Fick's law -> (i) Diffusion - L) Henry's law -> (iv) Gas-liquid phase transfer - M) Stoke's law -> (iii) Gravitational settling Select the correct option.

(A)

J-ii; K-i; L-iv; M-iii

(B)

J-iii; K-ii; L-i; M-iv

(C)

J-ii; K-iii; L-iv; M-i

(D)

J-i; K-iv; L-ii; M-iii

Explanation

GATE→2023→Air and Noise Pollution→Atmospheric Processes and Air Quality Parameters

Q11

NAT[2 Marks]

In a $30\text{ m}^3$ room, a stove in operation consumes wood at the rate of $0.25\text{ kg/h}$. The inflow and outflow rate of air in the room is the same, i.e. $500\text{ m}^3/\text{h}$. This stove emits a VOC species at a rate of $0.2\text{ g/kg}$ wood. The VOC species gets converted to $CO_2$ at a rate of $0.4\text{ per hour}$. Given: (i) the air in the room is completely mixed, (ii) initial concentration of the VOC species in the room is negligible, and (iii) concentration of the VOC species in the air entering the room is negligible. The concentration of the VOC species due to two hours of stove operation in the room is _____ (in $\mu\text{g/m}^3$, rounded off to one decimal place).

Explanation

GATE→2022→Air and Noise Pollution→Atmospheric Processes and Air Quality Parameters

Q12

MSQ[1 Mark]

$PM_{2.5}$ concentrations in ambient air can be measured using

(A)

Beta attenuation method

(B)

Chemiluminescence method

(C)

Gravimetric method

(D)

Non dispersive infrared spectroscopy method

Explanation

GATE→2022→Air and Noise Pollution→Atmospheric Processes and Air Quality Parameters

Q13

MSQ[2 Marks]

During night, in troposphere, which of the following is/are NOT correct?

(A)

$NO_2 + h\nu \rightarrow NO + O$

(B)

Most of the NOx (i.e., $NO + NO_2$) converts to NO

(C)

$NO + O_3 \rightarrow NO_2 + O_2$

(D)

Most of the NOx (i.e., $NO + NO_2$) converts to $NO_2$

Explanation

GATE→2022→Air and Noise Pollution→Atmospheric Processes and Air Quality Parameters

Q14

MSQ[2 Marks]

According to the National Ambient Air Quality Standards (Central Pollution Control Board, Govt. of India, notification 2009) which of the following statement(s) is/are correct?

(A)

$SO_2$ and $NO_2$ have annual average standards; while $O_3$ and CO have eight hour average standards.

(B)

$SO_2$ and CO have annual average standards; while $O_3$ and $NO_2$ have eight hour average standards.

(C)

$SO_2$ and CO have eight hour average standards; while $O_3$ and $NO_2$ have hourly average standards.

(D)

$SO_2$ and $NO_2$ have 24 hour average standards; while $O_3$ and CO have hourly average standards.

Explanation

Particulate Pollutants: Measurement and Control

7 Questions

GATE→2026→Air and Noise Pollution→Particulate Pollutants: Measurement and Control

Q15

MCQ[1 Mark]

In the design of air pollution control devices, size of the particles that are removed with 50% efficiency is termed as

(A)

mean size

(B)

mode size

(C)

cut size

(D)

median size

Explanation

GATE→2024→Air and Noise Pollution→Particulate Pollutants: Measurement and Control

Q16

MSQ[1 Mark]

The equipment that can be used to control particulate air pollution in an industrial unit is/are

(A)

Electrostatic precipitator

(B)

Cyclone separator

(C)

Gravity settler

(D)

Incinerator

Explanation

GATE→2024→Air and Noise Pollution→Particulate Pollutants: Measurement and Control

Q17

MCQ[2 Marks]

A gravity settling chamber of height '$H$' and length '$L$' is designed to control particulate air pollution. In the chamber, the horizontal velocity of air flow is '$V_h$' and terminal settling velocity of the target particle is '$V_t$'. Which one of the following expressions is the correct concept used to calculate the minimum size of the target particle that will be removed with $100\%$ efficiency?

(A)

\frac{V_t}{L} = \frac{V_h}{H}

(B)

V_h \times V_t = L \times H

(C)

V_h = V_t \times L \times H

(D)

\frac{V_t}{H} = \frac{V_h}{L}

Explanation

GATE→2024→Air and Noise Pollution→Particulate Pollutants: Measurement and Control

Q18

NAT[2 Marks]

In a cyclone separator of radius $25\text{ cm}$, a particle is travelling with a gas stream at velocity of $18\text{ m/s}$. The ratio of centrifugal force to the gravitational force acting on the particle is _____ (rounded off to 2 decimal places). (Consider $g = 9.8\text{ m/s}^2$)

Explanation

GATE→2023→Air and Noise Pollution→Particulate Pollutants: Measurement and Control

Q19

MCQ[2 Marks]

A boiler in an industry, located where high plume rise is expected, releases flue gas with fine particulate matter. Which one of the following options is most suited and efficient if this particulate matter is intended for reuse?

(A)

reduce stack height and increase stack diameter

(B)

use of wet collectors

(C)

use of flue gas desulfurization (FGD)

(D)

use of electrostatic precipitator (ESP)

Explanation

GATE→2022→Air and Noise Pollution→Particulate Pollutants: Measurement and Control

Q20

MCQ[1 Mark]

Which one of the following is most commonly used raw material in flue gas desulfurization units?

(A)

Limestone

(B)

Titanium Oxide

(C)

Fenton reagent

(D)

Beryllium Oxide

Explanation

GATE→2022→Air and Noise Pollution→Particulate Pollutants: Measurement and Control

Q21

MCQ[2 Marks]

A bag filter is used for removal of particulate matter having a range of sizes. The correct sequence of air filtration mechanisms for their removal, in order of decreasing size, is

(A)

Diffusion, Impaction, Disintegration

(B)

Disintegration, Impaction, Interception

(C)

Diffusion, Impaction, Interception

(D)

Impaction, Interception, Diffusion

Explanation

Air Quality Management and Dispersion Modelling

7 Questions

GATE→2026→Air and Noise Pollution→Air Quality Management and Dispersion Modelling

Q22

MCQ[2 Marks]

Which ONE of the following options CORRECTLY matches the atmospheric stability conditions with plume conditions/ behaviours given in the table?

(A)

(P) - (i); (Q) - (ii); (R) - (iii); (S) - (iv)

(B)

(P) - (iv); (Q) - (iii); (R) - (ii); (S) - (i)

(C)

(P) - (iii); (Q) - (iv); (R) - (ii); (S) - (i)

(D)

(P) - (ii); (Q) - (i); (R) - (iv); (S) - (iii)

Explanation

GATE→2026→Air and Noise Pollution→Air Quality Management and Dispersion Modelling

Q23

MSQ[2 Marks]

Which of the following options is/are CORRECT assumption(s) in the Gaussian plume dispersion model?

(A)

The concentration of pollutants emitting from stack is continuous.

(B)

The process is under steady state.

(C)

The pollutants emitted are non-conservative.

(D)

The diffusion of pollutants is dominant in comparison with advection in the direction of wind.

Explanation

GATE→2024→Air and Noise Pollution→Air Quality Management and Dispersion Modelling

Q24

MCQ[1 Mark]

The environmental temperature increases by $6^\circ\text{C/km}$ with height at a particular location. The stability condition of the atmosphere at the location is

(A)

stable

(B)

unstable

(C)

inversion

(D)

neutral

Explanation

GATE→2024→Air and Noise Pollution→Air Quality Management and Dispersion Modelling

Q25

NAT[2 Marks]

An industrial stack emits $100\text{ g/s}$ of $CO$ at an effective height of $H$, where the wind speed is $5\text{ m/s}$. At $3\text{ km}$ distance downwind, the values of dispersion coefficient in $y$-direction and $z$-direction are $50\text{ m}$ and $25\text{ m}$, respectively. The $CO$ concentration at the centerline of the plume at $3\text{ km}$ distance downwind is _____ $\text{mg/m}^3$ (rounded off to 2 decimal places). (Use Gaussian plume model and $\pi = 3.14$, ground-level centerline formula)

Explanation

GATE→2023→Air and Noise Pollution→Air Quality Management and Dispersion Modelling

Q26

NAT[2 Marks]

An industry with an effective stack height of $80\text{ m}$ emits $1200\text{ g/h}$ of $CO$. The windrose plotted using the meteorological data at the top of the stack, and the relation between dispersion coefficients and wind direction are given below: (Wind speed = $3\text{ m/s}$; Northeast wind frequency = $20\%$, highest frequency direction). Dispersion coefficients for Northeast: $\sigma_y = 50\text{ m}$, $\sigma_z = 20\text{ m}$. During the maximum duration of the year, the ground level concentration at the downwind distance of $2\text{ km}$ (at the plume centerline) from the stack is _____ (in $\mu\text{g/m}^3$, rounded off to two decimal places).

Explanation

GATE→2022→Air and Noise Pollution→Air Quality Management and Dispersion Modelling

Q27

MSQ[2 Marks]

Consider the figure shown below for three different cases (Case P, Case Q, Case R): Which of the following statement(s) is/are correct for surface level emissions, given the environmental temperature?

(A)

Case P represents unstable atmosphere and results in higher dispersion of emissions.

(B)

Case Q represents subsidence inversion and results in higher dispersion of emissions than Case P.

(C)

Case Q represents elevated inversion and results in lower dispersion of emissions than Case P.

(D)

Case R represents subsidence inversion and results in lower dispersion of emissions than Case P.

Explanation

GATE→2022→Air and Noise Pollution→Air Quality Management and Dispersion Modelling

Q28

NAT[2 Marks]

A ground level source emits $1000\text{ g per day}$ of $SO_2$. In vicinity of the source, ambient temperature is measured at $10\text{ m}$ and $110\text{ m}$ as $25^\circ\text{C}$ and $24.5^\circ\text{C}$, respectively. The mean wind speed is found to be $2\text{ m per second}$. The dispersion coefficients at $1000\text{ m}$ downwind distance from the source are given in table below... Estimated ground level concentration (in $\mu\text{g/m}^3$, rounded off to two decimal places) of $SO_2$ at a downwind distance of $1000\text{ m}$ (at the plume centerline) from the source is

Explanation

Noise Pollution

3 Questions

GATE→2026→Air and Noise Pollution→Noise Pollution

Q29

NAT[2 Marks]

The sound level measured at various locations in an urban area is given in the table. The average sound level for that area is _____ dBA (rounded off to two decimal places). Location: A (40 dBA), B (65 dBA), C (55 dBA), D (75 dBA)

Explanation

GATE→2024→Air and Noise Pollution→Noise Pollution

Q30

NAT[2 Marks]

Two sources of noise, adjacent to each other in a room, have sound pressure levels of $30$ and $40\text{ decibel (dB)}$. The combined sound pressure level in the room is _____ dB (rounded off to 2 decimal places).

Explanation

GATE→2022→Air and Noise Pollution→Noise Pollution

Q31

MCQ[2 Marks]

A relatively calm room has background sound power level (SPL) of $30\text{ decibels (dB)}$. A television and a radio with SPL of $80\text{ dB}$ and $70\text{ dB}$, respectively, started operating simultaneously in this room. Given the reference sound power is $10^{-12}\text{ Watts}$, what will be the resulting SPL in the room, assuming all the sources operate independently?

(A)

180.0 dB

(B)

80.4 dB

(C)

82.4 dB

(D)

150.0 dB

Explanation