Question

Clean water would have BOD value of less than ?

• A. $10\mathrm{ppm}$
• B. $20\mathrm{ppm}$
• C. $5\mathrm{ppm}$
• D. $12\mathrm{ppm}$

Answer 1

The correct option is C

$5\mathrm{ppm}$

Explanation for the correct option:

Option (C): $5\mathrm{ppm}.$

• The term BOD is known as the Biochemical Oxygen Demand.
• It is defined as the amount of dissolved oxygen that the aerobic bacteria require to decompose the organic waste present in the water sample.
• Drinking water is known to have a BOD level of $1-2\mathrm{ppm}.$
• When the BOD value of water is in the range $3-5\mathrm{ppm}$, the water is said to be moderately clean, hence this suggests that for clean water, the BOD value should be less than $5\mathrm{ppm}$.
• Whereas Polluted water has a BOD value in the range of $6-9\mathrm{ppm}.$and the value of BOD more than 100 ppm suggests, the water to be highly polluted.

Hence, the clean water should have a BOD value less than $5\mathrm{ppm}.$