Tag: planet earth

The pH of the acid rain is approximately 5-6.

When gases like $NO _2$ and $SO _3$ go into the atmosphere and react with water and form $H _2SO _4$ and $HNO _3$, these acids come along with rain water and hence it is known as acid rain.

Biological Oxygen Demand (BOD) refers to the amount of dissolved oxygen that aerobic organisms need in order to break down organic material in water over time. Its high value indicates the intense level of microbial pollution.

Maximum prescribed limit of Fe in drinking water is 50 ppm

Water pollution is the contamination of water bodies very often by human activities.

Pollutants which are slowly degradable remain in the environment in an unchanged form for many decades. For example, substances such as dichlorodiphenyltrichloroethane (DDT), plastic materials, heavy metals, many chemicals, and nuclear wastes etc., once released into the environment are difficult to remove. These pollutants cannot be degraded by natural processes and are harmful to living organisms. In the process of environmental pollution, pollutants originate from a source and get transported by air or water or are dumped into the soil by human beings.

All these industries cause water pollution by the water discharged into the rivers. The common industrial pollutants are sulphur, asbestos, poisonous solvents, poly-chlorinated biphenyl, lead, mercury, volatile organic chemicals, etc.

Water pollution is the contamination of water by substances harmful to life.

Pesticides and fertilizers containing chemicals causes water pollution. Pesticides contaminate water as the pesticides are toxic. Fertilizers contain nitrogen and phosphorous, high amount of which is injurious to the underwater organisms. Therefore, the answer is D.