Environmental Engineering Mcqs

Q:

The movement of particles from region of lower vapour to high vapour molecule concentration is known as diffusiophoresis.

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

Explanation: Movement of particles from higher vapour to low vapour molecule concentration is known as diffusiophoresis.

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78
Q:

Particle movement due to photophoresis depends on _________

A) Shape and size of the particle B) Optical properties of the particle
C) Wavelength and intensity of incident light D) All of the mentioned
 
Answer & Explanation Answer: D) All of the mentioned

Explanation: Particle movement due to photophoresis depends on the shape, size and optical properties of the particle, as well as wavelength and intensity of incident light.

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53
Q:

When a given gas has a temperature gradient, the aerosol particles move from higher temperature regions to low temperature regions. This effect is known as __________

A) Photophoresis B) Diffusiophoresis
C) Thermophoresis D) Diffusiophoresis or Thermophoresis
 
Answer & Explanation Answer: C) Thermophoresis

Explanation: Based on the temperature gradient, by the effect of thermophoresis, aerosol particles move from high temperature regions to low temperature regions.

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62
Q:

What is the statement of the Kelvin effect in fluid droplets?

A) Vapour pressure about a droplet decreases with decrease in diameter of the droplet B) Vapour pressure about a droplet increases with decrease in diameter of the droplet
C) Vapour pressure of the droplet is independent of the diameter of the droplet D) Vapour pressure of the droplet varies with the diameter of the droplet as well as the temperature
 
Answer & Explanation Answer: B) Vapour pressure about a droplet increases with decrease in diameter of the droplet

Explanation: The Kelvin effect is a phenomenon where the vapour pressure of the droplet increases with decrease in diameter of the droplet.

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90
Q:

The size of aerosol particles formed mechanically is minimum 1 micron.

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

Explanation: Due to surface tension, the minimum size of particles formed mechanically is limited to 1 micron.

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59
Q:

Formation of aerosols by nucleation produces particles of size __________

A) Less than 0.1 micron B) Greater than 0.1 micron
C) Less than 1 micron D) Greater than 1 micron
 
Answer & Explanation Answer: A) Less than 0.1 micron

Explanation: Aerosol formation by molecular nucleation leads to the production of particles with size less than 1 micron.

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86
Q:

Which of the following gases is responsible for the yellowing of the Taj Mahal?

A) Organic carbon B) Black carbon
C) Brown carbon D) All of the mentioned
 
Answer & Explanation Answer: D) All of the mentioned

Explanation: Organic carbon, black carbon and brown carbon (generated due to biomass combustion) are light absorbing particles responsible for the yellowing of the Taj Mahal.

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120
Q:

The acidic air pollutants reach the Earth’s surface because of wet deposition only.

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

Explanation: The acidic air pollutions get deposited on the Earth’s surface due to both wet and dry deposition. Wet deposition occurs due to rain fall and moist weather, whereas dry deposition occurs due to mixing of acidic pollutants and dust.

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