Question

At DO below $4$ mg/$l$, water at normal temperature is considered as

• A. Heavily polluted
• B. Moderately polluted
• C. Little polluted
• D. Nearly pure

Answer 1

Answer: (A)

Heavily polluted

Dissolved oxygen (DO) refers to the amount of oxygen dissolved in the water. It depends on the following factors:

1. Temperature- colder the temperature, more will be the DO.

2. Pressure- greater the pressure, more will be the DO.

3. Salinity- lower the salinity, more will be the DO.

The levels of DO below 5mg/l is considered to be hazardous to the aquatic lives. At normal temperature, any water body showing less DO than 5mg/l will be highly polluted.

Hence, the correct answer is 'Heavily Polluted'