Planet Earth : Online IGCSE Chemistry Class


Question 1
What is the composition of gases in our atmosphere?


Oxygen 21 per cent oxygen.
Carbon Dioxide 0.04%
Nitrogen 78 per cent nitrogen 
Inert Gas Argon makes up about 1% of the atmosphere 

Question 2
Please list the sources of pollution and their solutions

Pollution Sources Solutions
Water Pollution Factory waste

Domestic waste

Stop discharging toxic waste from factories into the river.
Prevent domestic waste that flows into the river and sea
Air Pollution Factory waste

Exhaust from transportation

The factory should use catalytic converters to filter air before releasing to the environment

Cars and transport vehicles should adopt battery-powered

Land Pollution Domestic waste Practice recycling and using biodegradable products


Question 3
Explain how the greenhouse effect occurs. (5 Points)

  • The greenhouse effect is gasses in the earth’s atmosphere that trap the sun’s heat. 
  • Greenhouse effects occur due to the excess discharge of carbon dioxide. 
  • Carbon dioxide is released by cars and factories
  • The trapped heat will make the earth hot which leads to global warming. 


Question 4:
What gas chemicals contributed to acid rain? (2m)
Sulfur dioxide and nitrogen oxides 


Question 5:
What are the problems caused by acid rains (2m)
Acid rain leaches aluminium from the soil. Aluminium may be harmful to plants as well as animals. 


Question 6:
Explain how depletion of the ozone layer causes health hazards. Explain with an example: (2m)

Ozone layer depletion causes increased UV radiation levels at the Earth’s surface, which is damaging to human health. Negative effects include increases in certain types of skin cancers, eye cataracts and immune deficiency disorders.


Question 7:
Below is the process of the water treatment plant

  1. Why does water need to be treated before drinking?
    To kill bacteria and filter suspended materials.
  2. What are the health hazards? Name a few diseases that relate to untreated water during drinking Cholera, hepatitis A, typhoid
  3. Why is a small amount of chlorine added to the water?
    It kills harmful microorganisms which are dangerous to health.
  4. Why is the distillation of seawater expensive for drinking?

The process takes longer to remove salt, and waste and requires complex filtrations.


Question 8:
Explain what are non-renewable sources of energy?
Non-renewable energy is an energy source that cannot be replenished


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