- No.6. Explain five important waterborne diseases. How can these be prevented?
Answer. The important waterborne diseases are
(i) Diarrhea diseases.
Intestinal diseases, such as cholera, that may cause dangerous dehydration. Diarrhea may be caused by viruses, bacteria, or parasites.
Cholera is an acute infection caused by the bacteria Vibrios choleroe, which may be found in water contaminated by human feaces. Cholera causes severe diarrhea and can be fatal.
It is liver inflammation commonly caused by one of five viruses called hepatitis A, B, C, D, and E. Hepatitis A and E can be transmitted by contaminated water.
(iv) . Jaundice
Jaundice is caused by an excess of bile pigments in the blood. Liver ceases to function and eyes turn yellow- Patient feels weakness and fatigue.
A dangerous, bacterial disease often spread by contaminated water or by food prepared with contaminated water.
Prevention of waterborne diseases
Waterborne diseases can be prevented by taking the following measures:
(i) Provision of safe water: Drinking water must be properly treated and purified.
(ii) Disposal of sewage: There must be adequate sanitary disposal of sewage. Any type of waste must not be thrown or discharged directly in water supplies or reservoirs.
(iii) Control of toxic chemicals: Chemical contamination can cause acute illness but often toxic contaminants are slow poisons and carcinogens. There must be a strict control over the use of pesticides and other chemicals.
- No.7. Give some disadvantages of hard water.
Answer. Some disadvantages of hard water are:
(i) Hard water consumes large amount of soap for washing purposes.
(ii) Drinking hard water causes stomach disorders.
(iii) Hard water is .unfit for use in steam engines, boilers and turbines because insoluble calcium and magnesium salts are deposited inside. They are bad conductors of electricity and hence more fuel is used. Insoluble calcium .and magnesium sulphates not only reduce the efficiency of the engine but also cause the boiler to burst,