Question

Statement (I): During an epidemic of infective hepatitis, the supplied water is super chlorinated.

Statement (II): Spore-forming bacteria which cause this disease are effectively removed from water by super chlorination.

1. Both Statement (I) and Statement (II) are individually true and Statement (II) is the correct explanation of Statement (I)
2. Both Statement (I) and Statement (II) are individually true but Statement (II) is not the correct explanation of Statement (I)
3. Statement (I) is true but Statement (II) is false
4. Statement (I) is false but Statement (II) is true

Answer 1

Correct Answer - Option 3 : Statement (I) is true but Statement (II) is false

In normal situations, dosage of chlorine in water is such a way that residual chlorine of 0.2 mg/l is left. However, in case of epidemic, chlorination is done in such a way that residual chlorine of 1 to 2 mg/l is left in water before sending in water in distribution network. This process is called super chlorination and it is done so that bacteria produced at later stages can be easily killed by residual chlorine in water.  

Super-chlorination is most commonly used when water has very high bacteria content and generally comes from river sources or where some form of heavy pollution or epidemic has occurred. The general dosage of super chlorination is in the range of 5 to 50 mg/l.

However, the spore forming bacteria cannot be killed by chlorination. It can be done by a process called sterilization which destroys spores and bacteria both. It is done at high temperature and under high pressure.