This set of Pollution Control Multiple Choice Questions & Answers (MCQs) focuses on “Characteristics and Sources of Particulates”.
1. Particulates refers to the substances in the atmosphere that are gaseous in nature.
a) True
b) False
View Answer
Explanation: Particulates refer to all the solid and liquid substances that get suspended in the atmosphere. Gases do not fall into the category of particulate matter, since they are another state of matter.
2. What is the reactive nature of particulates?
a) Inert and Reactive materials
b) Inert materials only
c) Reactive materials only
d) Moderately reactive materials only
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Explanation: Particulates can be both inert and reactive. They range from being slightly reactive to extremely reactive. The reactivity depends on several factors, one of them being photoactivity.
3. Which of the following is not a sub-classification of particulates?
a) Mist
b) Dust
c) Vapours
d) Smoke
View Answer
Explanation: Mist, dust, smoke, fog, et cetera are all classified as particulate matter, because they are made of solid or liquid particles. This classification is done based on the size of the particles and the nature of the particles itself.
4. What is the size range of dust particles?
a) Between 1 and 100 microns
b) Between 50 and 200 microns
c) Between 50 and 100 microns
d) Between 1 and 2 * 102 microns
View Answer
Explanation: Dust particles have a pretty wide range of sizes, from 1 micron to 200 microns. The larger the size of the particulate, the easier it is for the particle to settle under the influence of gravity.
5. How are natural dust particles formed?
a) Breakdown of rocks
b) Crushing processes
c) Grinding processes
d) Solids become airborne
View Answer
Explanation: Naturally, the breakdown of rocks and soil results in the formation of dust particles. In the industry, dust particles formation occurs due to size reduction processes like crushing and grinding.
6. How are dust particles removed from the atmosphere?
a) By air currents
b) due to gravity
c) They do not settle
d) By rain
View Answer
Explanation: Dust particles naturally settle back onto the surface of the earth due to the action of gravity. Their settling velocities are very high due to their size, so it is easy for them to settle onto the surface.
7. Which of the following is a function of dust particles when they are airborne?
a) Allergens
b) Bring rain
c) Reaction centre
d) Air pollutants
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Explanation: Since dust particles are mostly inert, they act as the reaction centres in the atmosphere. Water vapour droplets converge around dust particles in clouds, and other reactions also occur here.
8. What is the size range of smoke particles?
a) 0.01 to 100 micrometres
b) 10-2 to 102 micrometre
c) 1 to 100 micrometres
d) 10-2 to 1 micrometre
View Answer
Explanation: Smoke particles have a relatively narrow range of sizes, ranging from 10-2 micrometre to 1 micrometre. The range indicates, that they are very small as well. Smoke particles are solid particles made during the process of combustion.
9. Which of the following is not a source of smoke?
a) Forest fires
b) Internal combustion engines
c) Cooking
d) Size reduction operations
View Answer
Explanation: Combustion activities are responsible for the production of smoke. All the given options, expect size reduction operations, are sources of combustion. Hence, these sources are a source of smoke.
10. Smoke has different colours.
a) True
b) False
View Answer
Explanation: The colour of smoke varies with its origin, and its composition. Smoke from combustion engines and forest fires is black in colour because of soot. Soot is formed due to the incomplete combustion of fuels.
11. Which of the following statements about fumes is true?
a) Fume particles have the same size range as smoke
b) Fume particles have a size range of 10-2 to 1 micron
c) Fume particles have a size range of 10-1 to 1 micron
d) Fume particles have a size range of 10-2 to 10-1 microns
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Explanation: Fume and smoke particles do not have the same size range, so the given range of 10-2 to 1 micron is untrue. The size range of fume particles usually tend to fall in is between 10-2 to 1 micron.
12. Which of the following is an industrial source of fumes?
a) Paper and pulp
b) Metallurgical
c) Fertiliser
d) Petroleum refining
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Explanation: Generally, industrial sources like chemical manufacture and metallurgical industries release fumes. Fumes, like smoke, are solid particles, but their origins and sizes vary based on various reasons.
13. What is the range of sizes for mist particles?
a) Smaller than 0.1 microns
b) Smaller than 1 micron
c) Smaller than 10 microns
d) Smaller than 100 microns
View Answer
Explanation: Mist particles are very small in nature. They only have an upper limit on their range and no lower limit. Suspended liquid particles, which have sizes smaller than 10 microns are considered as mist.
14. What is the composition of smog?
a) Water
b) Liquids
c) Mist
d) Solids
View Answer
Explanation: Fog is essentially mist made of water particles. The water vapour condenses in the atmosphere, but the particles are denser than mist. Fog is made exclusively of water particles.
15. How is fog different from mist?
a) Mist is made of solid particles
b) Fog is made of solid particles
c) Mist particles are denser
d) Fog particles are denser
View Answer
Explanation: Fog and mist particles are both made of liquids. Fog is a kind of mist. Fog is made of suspended water particles and it is very dense. The particles of fog are dense enough reduce visibility.
Sanfoundry Global Education & Learning Series – Pollution Control.
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