Environmental Engineering Mcqs

Q:

What does the aerodynamic diameter of an aerosol indicate?

A) Size of the aerosol particle when floating in air B) Equivalent diameter of a sphere having same volume as that of the aerosol
C) Average diameter of aerosol particles present in unit volume of air D) Maximum size of aerosol particle that can float in the air
 
Answer & Explanation Answer: B) Equivalent diameter of a sphere having same volume as that of the aerosol

Explanation: The aero-dynamic diameter gives the equivalent diameter of a sphere having the same volume as that of the aerosol.

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5
Q:

What is the size of the particles categorised as aerosols?

A) Greater than 1 micron B) Less than 1 micron
C) Between 0.01-1 micron D) Less than 0.01 micron
 
Answer & Explanation Answer: C) Between 0.01-1 micron

Explanation: Aerosol consists of solid/fluid particles of size ranging between 0.01-1 microns.

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8
Q:

Aerosols contribute to global warming.

A) True B) False
 
Answer & Explanation Answer: B) False

Explanation: Aerosols help in scattering radiations from the sun back into outer space and help cool down the atmosphere.

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8
Q:

What type of colloid is an aerosol?

A) Solid in gas B) Gas in solid or fluid
C) Fluid in gas D) Fluid or solid in gas
 
Answer & Explanation Answer: D) Fluid or solid in gas

Explanation: Aerosol is a colloid formed by the presence of fluid or solid particles suspended in the air/atmosphere.

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8
Q:

What does CNC stand for in the context of aerosol particles?

A) Cloudy nucleic condensation B) Condensation nucleus counter
C) Chemical nucleic coagulation D) Cloudy nucleic coagulation
 
Answer & Explanation Answer: B) Condensation nucleus counter

Explanation: To measure the number concentration of aerosol particles, we use a condensation nucleus counter which counts particles of even 0.003 micron diameter.

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3
Q:

What is/are the inertial method(s) used to measure size of aerosol particles?

A) Particle acceleration method B) Pulsation method
C) Multi cyclone D) All of the mentioned
 
Answer & Explanation Answer: D) All of the mentioned

Explanation: Inertial methods such as particle acceleration, pulsation and multi-cyclones are used to measure size of aerosol particles larger than 5 microns.

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5
Q:

When light is passed through a suspension, it’s intensity decreases due to _________

A) Both scattering and diffraction B) Both diffraction and absorption
C) Absorption only D) Both scattering and absorption
 
Answer & Explanation Answer: D) Both scattering and absorption

Explanation: Light intensity decreases when passed through a suspension due to scattering and absorption of light by suspended particles.

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7
Q:

Which of the following scattering phenomena is responsible for the blue colour of the sky?

A) Mie scattering B) Diffraction
C) Rayleigh scattering D) All of the mentioned
 
Answer & Explanation Answer: C) Rayleigh scattering

Explanation: Due to Rayleigh’s scattering shorter wavelength radiations are scattered more, and hence makes the sky appear blue.

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