This document contains a Q&A chapter about air and the atmosphere. It discusses the composition of air, the carbon cycle, combustion reactions, and decreasing oxygen levels in caves. It also addresses environmental issues like haze from burning forests and the effects on health. The key points are:
- Nitrogen, oxygen, inert gases, and carbon dioxide make up the main components of air.
- Logging activities and burning fossil fuels increase carbon dioxide levels, contributing to global warming.
- Proper electrical wiring and smoke detectors can prevent fires caused by short circuits from happening.
- Decreasing oxygen levels in deep caves can be detected using an oxygen sensor for safety.
2. 1. The pie chart in Figure 1 shows the percentage of gas P, Q, R
and S in the atmosphere
(a) Determine gas
(i) P
(ii) Q
(iii) R
(iv) S
P: Nitrogen
Q: Oxygen
R: Inert gases
S: Carbon dioxide
3. (b) State the importance of gas P.
(c) What would happen to the temperature of Earth if the percentage of
gas S increases? Give a reason for your answer.
(d) Give one reason why air is considered a mixture.
• Needed to produce nitric acid and ammonia
• Helps in animal and plant growth
The temperature increases because gas S traps heat
Air components can be separated physically.
4. 2. Solve the crossword puzzle below with the correct answer.
Horizontal:
(a)Carbon cycle maintains
this gas in the air.
(b) This gas is used to fill
up light bulbs.
Vertical:
(c) A layer that surrounds
the Earth.
(d) This gas is needed in
combustion.
5. 3. Figure 2 shows the percentage of carbon dioxide in a period of
time.
6. (a) Logging activities increase the amount of carbon dioxide in the
atmosphere. How does it contribute to the increase of carbon dioxide
level in the atmosphere? Explain.
Green plants are the only living things that can absorb and reduce
carbon dioxide in the atmosphere through photosynthesis. When a
lot of trees are cut down, carbon dioxide which is released through
respiration, combustion and decomposition will increase the
percentage of carbon dioxide in the atmosphere.
7. (c) State two effects if the rate of carbon dioxide in the atmosphere
increases continuously
(b) Other than logging, give one activity that contributes to the
increase of carbon dioxide in the atmosphere.
Burning of fossil fuel / burning of forests
Greenhouse effect and global
warming
8. 4. Ammar witnessed a fire at a workshop on his way home from
school. The fire was caused by a short circuit.
(a) What is combustion?
(b) State the conditions of combustion.
Combustion is the reaction where a substance reacts with
oxygen chemically and produces heat and light energy
Heat, oxygen and fuel.
9. (c) Based on the situation,
(i) how does one prevent such a fire from happening?
(ii) what fire extinguisher is suitable?
Ensure electrical wirings are according to the right specifications
Use dry powder fire extinguisher.
10. (d) State three precautions that should be practised to prevent fire
from happening
• Install smoke detectors and fire alarm at home
• Do not plug in too many appliances on a single electrical source
• Always be aware of the electrical appliances used
11. 5. Figure 3 shows a situation that occurs in Kuala
Lumpur.
(a) What is the environmental
problem shown in Figure 3?
Haze
12. (b) State two effects of the problem you mentioned in 5(a) towards
health.
(c) The road accident rate increases when this environmental
problem occurs. Why?
Causes breathing difficulties and cough
The visibility distance is limited
13. 6. The oxygen level in a cave would eventually decrease as we walk
further into the cave.
14. (a)List a few reasons why the oxygen level decreases in the cave.
(b)If we want to go into a deep cave, we are encouraged to bring
torches with us in addition to torchlights as an indicator to show the
presence of oxygen. How does the torch function? Explain.
This is caused by natural processes such as the decay of
organisms like dead bats in the cave and the respiration of bats
or other animals inside the cave. This process reduces the
level of oxygen in the cave
The flame of the torch will extinguish when the oxygen level is
too low. Thus, the use of the torch can warn us not to continue
the exploration when we reach the area with low oxygen level.
15. (c) Do you think it is good to bring torches into the cave?
(d) Suggest one way to detect the oxygen level in a safer way. Give one
reason for your suggestion.
No, because we do not know the exact amount of oxygen in the
cave. In addition, the torch will increase the level of carbon dioxide
in the cave.
Use an oxygen sensor to know the exact level of oxygen and take
precautions.
