GATE Overflow for GATE ESE - Recent questions and answers in Particulate Pollutants

GATE ES 2026 | Question: 11

Mon, 23 Feb 2026 13:15:28 +0000

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

mean size
mode size
cut size
median size

GATE ES 2025 | Question: 50

Thu, 06 Mar 2025 16:20:59 +0000

A particle dispersoid has $1510$ spherical particles of uniform density. An air purifier is proposed to be used to remove these particles. The diameter specific number of particles in the dispersoid, along with the number removal efficiency of the proposed purifier is shown in the following table:
$$\begin{array}{|l|l|l|} \hline \text{Diameter of the} & \text{Number of particles} & \text{Number removal} \\ \text{particle} (\mu \mathrm{m}) && \text{efficiency} (\%) \\
\hline 1 & 1000 & 99 \\ \hline 10 & 500 & 75 \\ \hline 100 & 10 & 10 \\ \hline \end{array}$$

The overall mass removal efficiency of the proposed purifier is $\_\_\_\_\_ \: \%$. (rounded off to one decimal place)

GATE ES 2025 | Question: 51

Thu, 06 Mar 2025 16:20:57 +0000

An incandescent light bulb operated for two hours per day uses $12.2 \: \text{kWh}$ of energy per month. Burning of one kg of coal generates $2 \: \text{kWh}$ of electrical energy and releases $7 \: g$ of $\mathrm{PM}_{10}$. The reduction in $\mathrm{PM}_{10}$ emitted per month, if this incandescent bulb is replaced with a light emitting diode (LED) bulb which consumes $1 / 6^{\text {th }}$ of energy, is $\_\_\_\_\_ \: g$. (rounded off to one decimal place)

GATE ES 2024 | Question: 19

Mon, 19 Feb 2024 10:24:10 +0000

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

Electrostatic precipitator
cyclone separator
Gravity settler
Incinerator

GATE ES 2024 | Question: 31

Mon, 19 Feb 2024 10:24:08 +0000

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?

$\frac{V_{t}}{L}=\frac{V_{h}}{H}$
$V_{h} \times V_{t}=L \times H$
$V_{h}=V_{t} \times L \times H$
$\frac{V_{t}}{H}=\frac{V_{h}}{L}$

GATE ES 2023 | Question: 30

Tue, 23 May 2023 03:12:11 +0000

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?

reduce stack height and increase stack diameter
use of wet collectors
use of flue gas desulfurization $\text{(FGD)}$
use of electrostatic precipitator $\text{(ESP)}$

GATE ES 2021 | Question: 36

Tue, 14 Mar 2023 03:44:04 +0000

Which of the following isiare the dominant mechanism(s) for the removal of spherical particles with diameter less than $10 \mu \mathrm{m}$ from a gas stream using a fabric filter?

Impaction
Gravitation
Interception
Diffusion

GATE ES 2022 | Question: 20

Fri, 17 Feb 2023 07:05:56 +0000

$\quad \mathrm{PM}_{2.5}$ concentrations in ambient air can be measured using

Beta attenuation method
Chemiluminescence method
Gravimetric method
Non dispersive infrared spectroscopy method

GATE ES 2022 | Question: 31

Fri, 17 Feb 2023 07:05:49 +0000

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

Diffusion, Impaction, Disintegration
Disintegration, Impaction, Interception
Diffusion, Impaction, Interception
Impaction, Interception, Diffusion