Chemistry - Study Mode

[#741] Hard water and soft water can be distinguished by using
Correct Answer

(C) Detergent

Explanation

Solution: Hard water and soft water can be distinguished by using detergent.

[#742] Which method will be employed to test the hardness of water?
Correct Answer

(C) Formation of lather with soap

Explanation

Solution: Soap solution is used to measure the hardness of rain water, temporarily hard water and sea-water. Hard water does not form soap lather. This is because magnesium ions or calcium ions present in hard water react with soap to form calcium stearate or magnesium stearate and thus forms scum.

[#743] The purest form of water is
Correct Answer

(B) Rain water

Explanation

Solution: The purest form of water is rain water.

[#744] Water cycle refers to
Correct Answer

(B) Constant movement of water from ocean to land and back to ocean once again

Explanation

Solution: Water cycle, also called hydrologic cycle, cycle that involves the continuous circulation of water in the Earth-atmosphere system. Of the many processes involved in the water cycle, the most important are evaporation, transpiration, condensation, precipitation, and runoff. Although the total amount of water within the cycle remains essentially constant, its distribution among the various processes is continually changing.

[#745] Permanent hardness of water may be removed by addition of
Correct Answer

(B) Sodium carbonate

Explanation

Solution: Hardness can be removed by adding sodium carbonate (washing soda) or by passing the water through an ion-exchange column.