GRADE 9 Integrated Science – Water hardness Quiz
1. What is the main cause of water hardness?
Water hardness is primarily caused by the presence of calcium and magnesium ions in the water, which can form scale deposits.
2. Which process can be used to remove temporary hardness from water?
Boiling can be used to remove temporary hardness from water as it causes the calcium and magnesium ions to precipitate out.
3. What is the unit of measurement for water hardness?
Water hardness is typically measured in degrees, which represents the amount of calcium carbonate present in the water.
4. Which of the following is not a method of treating water hardness?
Adding calcium chloride would only further increase the hardness of the water, making it an ineffective method for treating water hardness.
5. What effect does water hardness have on soap?
Water hardness reacts with soap to form insoluble scum, which reduces the lathering ability of the soap.
6. Which of the following best describes permanent hardness?
Permanent hardness is caused by the presence of sulfates and chlorides of calcium and magnesium, which cannot be removed by boiling.
7. What is the common method used to treat permanent hardness in water?
Permanent hardness can be treated by adding sodium carbonate (washing soda) which reacts with the calcium and magnesium ions to form insoluble precipitates.
8. Which type of water hardness can be easily removed by boiling?
Temporary hardness can be removed by boiling as it causes the calcium and magnesium ions to precipitate out of the water.
9. What is the main source of water hardness in most groundwater sources?
Most groundwater sources contain water hardness due to the dissolution of calcium and magnesium ions from limestone and dolomite rocks.
10. How does water hardness affect the taste of water?
Water hardness does not have a direct impact on the taste of water, although it can affect the flavor of beverages prepared with hard water.
11. Which of the following does not contribute to water hardness?
Chloride ions do not contribute to water hardness. Water hardness is primarily caused by the presence of calcium and magnesium ions.
12. What is the unit of measurement for water hardness?
Water hardness is measured in parts per million (ppm), which indicates the concentration of calcium and magnesium ions in the water.
13. How does temporary hardness differ from permanent hardness?
Temporary hardness is caused by the presence of bicarbonates of calcium and magnesium, which can be removed by boiling. Permanent hardness is caused by sulfates and chlorides of calcium and magnesium, which cannot be removed by boiling.
14. What is the main cause of water hardness in most Kenyan water sources?
Calcium ions are the main cause of water hardness in most Kenyan water sources. These ions come from the surrounding rocks and soil.
15. Which method is commonly used to soften hard water in households?
Water softeners are commonly used in households to remove calcium and magnesium ions from hard water, making it softer and more suitable for daily use.
16. What is the main cause of water hardness?
Water hardness is mainly caused by the presence of calcium and magnesium ions in the water. These ions can react with soap to form scum.
17. Which process can be used to remove temporary hardness from water?
Boiling water helps to remove temporary hardness as it causes the calcium carbonate to precipitate out of the water.
18. What is the most common method used to measure water hardness?
Titration is the most common method used to measure water hardness as it involves adding a chemical solution to determine the calcium and magnesium content.
19. What is the acceptable level of water hardness for drinking water in Kenya?
The acceptable level of water hardness for drinking water in Kenya is 50 ppm (parts per million) to ensure it is safe for consumption.
20. Which ions contribute to permanent hardness in water?
Permanent hardness is mostly caused by the presence of calcium and magnesium ions in the water, which can be challenging to remove.