Displaying items by tag: Water
Water - Class 6 Science Revision Notes
Waterborne Diseases
They are diseases that are spread through contaminated water. They include:
- Cholera
- Typhoid
- Bilharzia.
Cholera
It is caused by bacteria. it can cause death within 24 hours if not treated. It causes death through dehydration.
Signs and Symptoms
- Violent diarrhoea (rice water).
- Vomiting.
- Severe abdominal pains
- Wrinkled skin due to dehydration.
- Sunken eyeballs
Typhoid
It mainly affects the intestines. It is also known as typhoid fever.
Signs and Symptoms
- Pain in the joints and muscles
- High fever
- Abdominal pains
- Skin rash
Bilharzia
It is caused by bilharzia worms or blood flukes. It is carried by water snails.
The disease mainly affect the bladder and intestines
Bilharzia worms enter the body through the skin.
Signs and Symptoms
- Blood in urine and stool
- Coughing may occur
- Abdominal pain
- Swimmers itch
- Fever
Water - Class 7 Science Revision Notes
Water Pollution
This involves making water impure or contaminating it.
Causes of Water Pollution
- Floods
- Human and animals waste
- Oil spillage
- Waste from industries.
- Uncontrolled use of farm chemicals.
- Acid rain
Effects of Water Pollution.
- Blocking the root hair.
- Acidic rain causes harm to plants since they cannot grow well in acidic rain.
- Dissolved chemicals substances and fertilizer may cause harm to animals.
- Oil spillage prevents entry of oxygen in water leading to suffocation and death.
Controlling Water Pollution.
- Practising proper hygiene.
- Practising farming methods.
- Drawing water for animals instead of taking them to water sources.
- Controlling the dumping of industrial waste into water sources.
- Clearing accidental oil spills as soon as they happen.
- Controlling the use of farm chemicals.
Conservation of Water
Conservation means proper care and use of water sources.
It ensures water isused sparingly and conserved for future use.
Ways of Conserving Water.
- Harvesting rain water.
- Recycling water.
- Re-using water.
- Using water sparingly.
- Mulching and shading.
- Construction of dams
Water - class 8 science revision notes
Hard and soft water.
Hard water is water which contains dissolved salts ie magnesium and calcium. Mainly from sea,
oceans, boreholes, lakes and dams.
Soft water is water with no or little dissolved salt in it. Mainly rain water.
Advantages of hard water.
- Contains dissolved minerals which are good for our health.
- It has a good taste to drink.
- It is good in brewing industry.
Disadvantages of hard water.
- Wastes a lot of soap because it does not lather easily.
- It discolours teeth when drank.
- It stains clothes.
- It causes clogging and blocking of pipes.
- It forms scales or fur on boilers and hot water pipes.
- Wastes a lot of time and energy during laundry.
Advantages of soft water.
- Does not stains teeth.
- Best in laundry.
Disadvantages of soft water.
- Does not have a good taste.
- Has no minerals required by the body.
Types of water hardness.
There are two types of water hardness, namely;
- Temporary water hardness.
- Permanent water hardness.
Temporary water hardness can be removed by boiling or distillation. Permanent water hardness can be removed by adding chemicals.
NB: The process of removing the dissolved minerals from hard water is called softening.