BOD values (in ppm) for clean water (A) and polluted water (B) are expected respectively :
Question:

BOD values (in ppm) for clean water (A) and polluted water (B) are expected respectively :

1. $\mathrm{A}>50, \mathrm{~B}<27$

2. $A>25, B<17$

3. $A<5, B>17$

4. $\mathrm{A}>15, \mathrm{~B}>47$

Correct Option: , 3

Solution:

BOD values of clean water (A) is less than $5 \mathrm{ppm}$

So $A<5$

BOD values of polluted water (B is greater than 17 ppm

So    $\mathrm{B}>17$

So Ans. is 3