GATE CE topic:air-pollution PYQs & Answers

Questions 1–10 of 29. Imported answers require independent review unless marked reviewed.

Column I presents common air pollutants, and column II presents treatment technologies commonly employed to control air pollutants.

Air pollutant	Treatment technology
1	Dust (size 5-25 m)	P	Cyclone separator
2	Carbon monoxide (CO)	Q	Wet lime-water scrubber
3	Sulfur dioxide (SO )	R	Electrostatic precipitator
4	Fly ash (size < 2.5 m)	S	Catalytic converter

The option that CORRECTLY matches the air pollutant with its treatment technology is:

Your answerChoose one option.

1 – P ; 2 – S ; 3 – Q ; 4 – R

1 – P ; 2 – R ; 3 – S ; 4 – Q

1 – R ; 2 – Q ; 3 – P ; 4 – S

1 – R ; 2 – Q ; 3 – S ; 4 – P

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In an industry, a cyclone collector with 80 % efficiency is installed for air purification, followed by an electrostatic precipitator with 50 % efficiency. The concentration of particles entering the cyclone collector is 10 mg/m³.

The concentration (in mg/m³) of particles exiting the precipitator is ______ (rounded off to two decimal places).

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A hydrocarbon (CₙHₘ) is burnt in air (O₂ + 3.78N₂). The stoichiometric fuel to air mass ratio for this process is

Note: Atomic Weight: C(12), H(1)

Effective Molecular Weight: Air(28.8)

Ignore any conversion of N₂ in air to the oxides of nitrogen (NOₓ)

Your answerChoose one option.

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A settling chamber is used for the removal of discrete particulate matter from air with following conditions. Horizontal velocity of air = 0.2 m/s; Temperature of air stream = 77°C; Specific gravity of particle to be removed = 2.65; Chamber length = 12 m; Chamber height = 2 m; Viscosity of air at 77°C = 2.1 x 10

kg/m.s; Acceleration due to gravity (g) = 9.81 m/s

; Density of air at 77°C =1.0 kg/m

; Assume the density of water as 1000 kg/m

and Laminar condition exists in the chamber.

The minimum size of particle that will be removed with 100% efficiency in the settling chamber (in

m) is ______ (round off to one decimal place).

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What is the CORRECT match between the air pollutants and treatment techniques given in the table?

Air pollutants	Treatment techniques
P - NO₂	i - Flaring
Q - SO₂	ii - Cyclonic separator
R - CO	iii - Lime scrubbing
S - Particles	iv - NH₃ injection

Your answerChoose one option.

P-i, Q-ii, R-iii, S-iv

P-ii, Q-i, R-iv, S-iii

P-ii, Q-iii, R-iv, S-i

P-iv, Q-iii, R-i, S-ii

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The primary air pollutant(s) is/are

Your answerSelect all correct options. You can choose more than one.

Sulphur dioxide

Lead

Ozone

Sulphuric acid

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For assessing the compliance with the emissions standards of incineration plants, a correction needs to be applied to the measured concentrations of air pollutants. The emission standard (based on 11% Oxygen) for HCl is 50 mg/Nm³ and the measured concentrations of HCl and Oxygen in flue gas are 42 mg/Nm³ and 13%, respectively.

Assuming 21% Oxygen in air, the CORRECT statement is:

Your answerChoose one option.

No compliance, as the corrected HCl emission is greater than the emission standard.

Compliance is there, as the corrected HCl emission is lesser than the emission standard.

Compliance is there, as there is no need to apply the correction since Oxygen is greater than 11% and HCl emission is lesser than the emission standard.

No compliance, as the Oxygen is greater than 11% in the flue gas.

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An organic waste is represented as C

(Atomic weights: S-32, H-1, C-12, O-16, N-14).

Assume complete conversion of S to SO

while burning.

generated (in grams) per kg of this waste is __________ (rounded off to 1 decimal place).

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Which one of the following statements is TRUE for Greenhouse Gas (GHG) in the atmosphere?

Your answerChoose one option.

GHG absorbs the incoming short wavelength solar radiation to the earth surface, and allows the long wavelength radiation coming from the earth surface to pass through

GHG allows the incoming long wavelength solar radiation to pass through to the earth surface, and absorbs the short wavelength radiation coming from the earth surface

GHG allows the incoming long wavelength solar radiation to pass through to the earth surface, and allows the short wavelength radiation coming from the earth surface to pass through

GHG allows the incoming short wavelength solar radiation to pass through to the earth surface, and absorbs the long wavelength radiation coming from the earth surface

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Match the following air pollutants with the most appropriate adverse health effects:

Air pollutant	Health effect to human and/or test animal
(P) Aromatic hydrocarbons	(I) Reduce the capability of the blood to carry oxygen
(Q) Carbon monoxide	(II) Bronchitis and pulmonary emphysema
(R) Sulfur oxides	(III) Damage of chromosomes
(S) Ozone	(IV) Carcinogenic effect

Your answerChoose one option.

(P) – (II), (Q) – (I), (R) – (IV), (S) – (III)

(P) – (IV), (Q) – (I), (R) – (III), (S) – (II)

(P) – (II), (Q) – (I), (R) – (II), (S) – (IV)

(P) – (IV), (Q) – (I), (R) – (II), (S) – (III)

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GATE CE topic:air-pollution PYQs

How to practice topic:air-pollution

Question 27

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