Question

Which of the following will make water free from all impurities?
A.Adding chlorine tablets
B.Distillation
C.Boiling
D.Filtration

Answer 1

Hint:We will have to check all the options and find out whether it helps in purification of water from impurities or not. We will also check the methods to remove temporary hardness and permanent hardness etc.

Complete step by step solution:
The first option is adding chlorine tablets.
Adding chlorine tablets to water is widely used for disinfecting water. Disinfection kills most of the viruses and bacteria present in water. These chlorine tablets can make water suitable for washing vegetables, fruits etc. But these tablets will not make water completely free from impurities.
The next option is distillation. The tank in which distillation is done is known as distiller.
Distillers are commonly used for removing nitrate, bacteria, sodium, hardness (dissolved solids), most organic compounds, heavy metals and radionuclides from water. Distillers remove about 99.5% of the impurities from the original water. Distillation procedures will give us water free from all impurities. The distillation process removes almost all impurities from water.
So this option can be the answer but before that we will also check the remaining options.
The third option is boiling.
Boiling water kills or inactivates viruses, bacteria, protozoa and other pathogens by using heat to damage structural components and disrupt essential life processes (e.g. denature proteins). So we can get rid of these microorganisms present in water.
There are two types of hardness present in water temporary hardness and permanent hardness.
So this option is not correct.
The fourth option is filtration.
Water filtration is the process of removing or reducing the concentration of particulate matter, including suspended particles, parasites, bacteria, algae, viruses, and fungi, as well as other undesirable chemical and biological contaminants from contaminated water to produce safe and clean water. But there is also one drawback with this method and i.e. dissolved impurities cannot be separated.

After analyzing each method we find the correct answer is option B. Distillation.

Note:
Boiling cannot remove permanent hardness from water. So boiling is not sterilization and is more accurately characterized as pasteurization.Also it should be noted that distillation is a physical process.