The value of BOD of highly polluted water is-
more than 17 ppm
in between 5 to 10 ppm
1 ppm
5ppm

B.O.D values of four samples of water A,B,C and D are given below A 160 ppm B 35 ppm C 180 ppm D 25 ppm

Biochemical oxygen demand values off our water samples A, B, C and D are respectively 50 ppm, 100 ppm, 150 ppm and 40 ppm. Arrange them in the descending order of their purity.

Dissolved oxygen values of four water samples A, B, C and D are respectively 1 ppm, 3ppm, 5 ppm and 7 ppm. Which is more polluted ?

Assertion : BOD of river polluted by sewage is more than 20 ppm. Reason: Polluted river contains excess of organic matter.

Assertion : The amount of BOD in the water is a measure of the amount of organic material in the water . Reason : Clear water has BOD less than 5 ppm whereas highly polluted water can have BOD value of 17 ppm or more .