This set of Air Pollution Control Multiple Choice Questions & Answers (MCQs) focuses on “Gaseous Pollutants Control – Mobile Sources”.
1. Which of the following is not a primary pollutant released from mobile sources?
a) Carbon monoxide
b) Nitrogen oxides
c) Hydrocarbons
d) Sulphur dioxide
View Answer
Explanation: There are two distinct types of combustion sources: stationary and mobile. Mobile sources of combustion are cars, trucks and other moving vehicles. Common pollutants released from such sources are carbon monoxide, nitrogen oxides, and hydrocarbons.
2. What is the difference between the pollutants released from petrol and diesel engines?
a) The quantity
b) The proportions
c) The emissions over time
d) There is no difference
View Answer
Explanation: The emissions from petrol and diesel engines vary in the proportion of each kind of pollutant released. The quantities are comparable. The emissions from petrol engines are almost colourless, while emissions of diesel engines vary (white, blue, black).
3. Which of the following parts releases the most amount of pollutants from an automobile?
a) The evaporations from the fuel tank
b) The crankcase
c) The exhaust pipe
d) Combustion chamber
View Answer
Explanation: The exhaust pipes release a large chunk of the pollutants from automobiles, about 70%. About 20% is released from the crankcase. The rest (about 10%) is released from evaporation in the fuel tank, as well as the carburettor of the car.
4. What is the main limitation of trying to control the emissions from mobile sources?
a) Suppression of one pollutant results in the increase in output of others
b) Control is impossible because mobile sources are moving
c) It increases the cost of the vehicle
d) Control is impossible because of the increased space requirement
View Answer
Explanation: The main limitation of controlling the emissions from moving sources is that the control of one pollutant causes an increase in other pollutant emissions. For example, a rich fuel-to-air ratio would release less NOx but higher CO and hydrocarbons.
5. What will happen if stoichiometric fuel to air ratio is used for combustion?
a) High levels of nitrogen oxides
b) High levels of Carbon monoxide
c) High levels of hydrocarbons
d) High energy production
View Answer
Explanation: A stoichiometric fuel to air ratio for the combustion process means that there is only enough oxygen for fossil fuel oxidation. This limitation results in lower emissions of carbon monoxide and hydrocarbons. However, an increase in the emissions of nitrogen oxides is observed.
6. What happens when high fuel-to-air ratios are used for combustion?
a) High NOx release
b) Engine design problems
c) High CO release
d) It cannot be said
View Answer
Explanation: High fuel-to-air ratios are ideal for controlling the emissions of nitrogen oxides, carbon monoxide, and hydrocarbons. However, this change causes design problems. Additionally, the ratios should not be allowed to increase too much, or hydrocarbon emissions increase further.
7. Which of the following is not a control method for pollutant reduction from mobile sources?
a) Modification of internal combustion engine
b) Use exhaust system reactors
c) Substitute fuels
d) Replace old cars with new cars
View Answer
Explanation: Replacing older cars with newer cars helps with pollutant emissions. However, it is not a control method. Modification of internal combustion engine, using exhaust system reactors, and substituting fuels are all control methods.
8. How can an internal combustion engine be modified?
a) Better understanding of combustion
b) Change fuel to air ratios
c) Control combustion better
d) Use catalyst
View Answer
Explanation: The reason for modifying the combustion engine is to control the combustion thoroughly. The engine, then, can be modified to have electronic fuel injection, using new ignition methods instead of spark plugs, et cetera.
9. Which pollutants do exhaust system reactors reduce?
a) Carbon monoxide
b) Nitric oxide
c) Sulphur dioxide
d) Nitric oxide
View Answer
Explanation: Primarily, exhaust system reactors are used to control the emissions of carbon monoxide and various hydrocarbons. The reactors, which may be of two types (mainly catalytic and thermal), are being incorporated increasingly in automobiles.
10. Which of the following is not a petrol substitute?
a) Methanol
b) Methanal
c) Hydrogen
d) Methane
View Answer
Explanation: Common petrol substitutes are methanol, hydrogen, and methane. Methane is also known as natural gas. Methanal is formaldehyde, which is not used as a fuel. These fuels release significantly fewer pollutants.
11. What is the primary problem with using turbine engines in cars?
a) Turbines are not used
b) Temperatures required are too high
c) Poor fuel economy
d) Noise pollution
View Answer
Explanation: Turbines are an alternative to internal combustion engines. These machines have a lesser number of moving parts than internal combustion engines. However, the disadvantages of turbines include low fuel economy, especially at low fuel loads.
Sanfoundry Global Education & Learning Series – Air Pollution Control.
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