Question

Ozonation of water is carried to remove:
(A) Bacterial impurities
(B) Bad taste
(C) Excess chlorine present
(D) Calcium and magnesium salts present in it

Answer 1

Hint: Ozonation of water is done for the purification of water. We know that the purification of water is done to remove the unwanted chemicals, biological contaminants, suspended solids, gases, etc. from water.

Complete step by step solution:We know that ozone is an unstable gas. It contains three oxygen atoms. The molecular formula for ozone is ${{\text{O}}_{\text{3}}}$. Being unstable in nature, ozone degrades within a few seconds.
Ozone is a colourless gas. Its odour is similar to the smell of the air after a major thunderstorm. Ozone is seen effective over a wide range of pH.
Being unstable ozone readily gets back to oxygen or a free radical form. The free radical form of ozone is short lived and is highly reactive. Under normal conditions, the free radical form of ozone survives for milliseconds only.
Ozone reacts rapidly with bacteria, viruses and protozoans. Ozone has a strong germicidal property and a strong oxidising power with a short reaction time.
Ozone eliminates a wide variety of microbial problems from water. The microbial agents include bacteria, viruses, protozoans such as Giardia and Cryptosporidium.
Thus, ozonisation of water is carried out to remove bacterial impurities.

Thus, the correct option is (A) bacterial impurities.

Note: It should be noted that there are disadvantages of ozonation are also which as follows:
-The equipment and operational cost is very high.
-The solubility of ozone in water is very low. Thus, we need special techniques for mixing.
-The by-products of ozonation may be carcinogenic.
-There are potential fire hazards associated with ozonation.