Air & Atmosphere - Multiple Choice Questions Quiz

1. Which of the following is needed for the combustion of substances?

Nitrogen

Carbon dioxide

Oxygen

Noble gases

Oxygen is needed for the combustion of substances because it is a highly reactive gas that supports the chemical reaction of burning. During combustion, oxygen molecules react with the fuel molecules, breaking their chemical bonds and releasing energy in the form of heat and light. Without oxygen, combustion cannot occur as there would be no source of oxygen atoms to combine with the fuel molecules. Nitrogen, carbon dioxide, and noble gases do not play a direct role in the combustion process.

Explanation

Oxygen is needed for the combustion of substances because it is a highly reactive gas that supports the chemical reaction of burning. During combustion, oxygen molecules react with the fuel molecules, breaking their chemical bonds and releasing energy in the form of heat and light. Without oxygen, combustion cannot occur as there would be no source of oxygen atoms to combine with the fuel molecules. Nitrogen, carbon dioxide, and noble gases do not play a direct role in the combustion process.

2. Carbon monoxide is a pollutant emitted from the car exhaust system. Which of the following reasons explain why carbon monoxide is considered as an air pollutant?

It is odourless and colourless

It causes lung cancer

It forms acid rain which corrodes buildings made of limestone

It causes breathing difficulties by preventing the absorption of oxygen

Carbon monoxide is considered an air pollutant because it causes breathing difficulties by preventing the absorption of oxygen. This is because carbon monoxide has a higher affinity for hemoglobin in the blood than oxygen, leading to a decrease in the amount of oxygen that can be transported to the body's tissues. This can result in symptoms such as shortness of breath, dizziness, and even death in severe cases.

Explanation

Carbon monoxide is considered an air pollutant because it causes breathing difficulties by preventing the absorption of oxygen. This is because carbon monoxide has a higher affinity for hemoglobin in the blood than oxygen, leading to a decrease in the amount of oxygen that can be transported to the body's tissues. This can result in symptoms such as shortness of breath, dizziness, and even death in severe cases.

3. Which of the following processes will not affect the carbon cycle?

Photosynthesis

Respiration

Combustion

Neutralisation

Photosynthesis removes carbon dioxide in the atmosphere.
Both respiration and combustion adds carbon dioxide to the atmosphere.
Neutralisation does not affect the carbon cycle.

Explanation

Photosynthesis removes carbon dioxide in the atmosphere.
Both respiration and combustion adds carbon dioxide to the atmosphere.
Neutralisation does not affect the carbon cycle.

4. Car exhausts are a major source of pollution by nitrogen oxides. Which statement explains how the oxides are produced?

The oxides are produced by the catalytic converter in the exhaust

The oxides are produced from the combustion of impurities in the car's fuel

Heat from the engine makes atmospheric nitrogen and oxygen react together

The oxides are produced due to incomplete combustion of the fuel

The correct answer is "Heat from the engine makes atmospheric nitrogen and oxygen react together." When the engine of a car heats up, it causes the atmospheric nitrogen and oxygen to react and form nitrogen oxides. This reaction occurs due to the high temperatures reached during combustion in the engine.

Explanation

The correct answer is "Heat from the engine makes atmospheric nitrogen and oxygen react together." When the engine of a car heats up, it causes the atmospheric nitrogen and oxygen to react and form nitrogen oxides. This reaction occurs due to the high temperatures reached during combustion in the engine.

5. The burning of fossil fuels releases an air pollutant which attacks limestone and buildings. Which of the following is the air pollutant released?

Carbon monoxide

Carbon dioxide

Oxides of nitrogen

Sulfur dioxide

Both sulfur dioxide and oxides of nitrogen causes acid rain which corrodes buildings.
However, only sulfur dioxide is produced from the burning of fossil fuels.

Explanation

Both sulfur dioxide and oxides of nitrogen causes acid rain which corrodes buildings.
However, only sulfur dioxide is produced from the burning of fossil fuels.

6. Which of the following substances is not found in a clean air sample?

Oxygen

Nitrogen

Hydrogen

Helium

Air is made up of nitrogen, oxygen, carbon dioxide and noble gases.
Helium is a noble gas. Hydrogen does not belong to any of these categories.

Explanation

Air is made up of nitrogen, oxygen, carbon dioxide and noble gases.
Helium is a noble gas. Hydrogen does not belong to any of these categories.

7. 120 cm³ of air is heated with phosphorus to form phosphorus (V) oxide in the air. After the reaction, what is the volume of air which remained?

120

24

96

55

The oxygen has reacted with phosphorus.
There is 20% of oxygen in the composition of air,
Amount of oxygen reacted: 20% of 120 = 24
Remaining volume of air: 120 - 24 = 96

Explanation

The oxygen has reacted with phosphorus.
There is 20% of oxygen in the composition of air,
Amount of oxygen reacted: 20% of 120 = 24
Remaining volume of air: 120 - 24 = 96

8. Which gas is not produced when hydrocarbons are burnt in the internal combustion engines?

Carbon dioxide

Carbon monoxide

Hydrogen

Oxides of nitrogen

Complete combustion produces H2O and CO2.
Incomplete combustion produces CO.
Oxides of nitrogen are produced around the engines at high temperatures. N2 + 2O2 + heat --> 2NO2
Hydrogen is not produced.

Explanation

Complete combustion produces H2O and CO2.
Incomplete combustion produces CO.
Oxides of nitrogen are produced around the engines at high temperatures. N2 + 2O2 + heat --> 2NO2
Hydrogen is not produced.

9. Unpolluted rain water has a pH of about 6. Which of the following gas causes this pH?

Carbon dioxide

Oxygen

Nitrogen dioxide

Sulfur dioxide

pH 6 is slightly acidic.
Carbon dioxide dissolves in water to form carbonic acid, which is slightly acidic.
CO2 + H2O --> H2CO3
Nitrogen dioxide dissolves to form nitric acid while sulfur dioxide dissolves to form sulfuric acid, with a pH of about 3.

Explanation

pH 6 is slightly acidic.
Carbon dioxide dissolves in water to form carbonic acid, which is slightly acidic.
CO2 + H2O --> H2CO3
Nitrogen dioxide dissolves to form nitric acid while sulfur dioxide dissolves to form sulfuric acid, with a pH of about 3.

10. A tyre of a lorry is made by heating together a mixture of sulfur and rubber. Rubber is a hydrocarbon. What are the products if the tyre is completely burnt in air?

Carbon monoxide, carbon dioxide, sulfur dioxide, water

Carbon dioxide, sulfur dioxide

Carbon dioxide, sulfur dioxide, water

Carbon dioxide, carbon monoxide, water

Sulfur reacts with oxygen to form sulfur dioxide.
S (g) + O2 (g) --> 2SO2 (g)
Hydrocarbon burns completely to form carbon dioxide and water.

Explanation

Sulfur reacts with oxygen to form sulfur dioxide.
S (g) + O2 (g) --> 2SO2 (g)
Hydrocarbon burns completely to form carbon dioxide and water.