Give reason :

(a) Presence of high levels of suspended particles in the air is harmful for us.

(b) A sudden change in the temperature of the water body is dangerous for the aquatic life of the water body.

(c) The process of Nitrogen fixation by bacteria does not take place in presence of oxygen.

Plzzzzzz it's urgent

(c)There are methods that change atmospheric nitrogen into usable forms through the process of nitrogen fixation. Two such methods are given below. 

[1]. During lightning and thunder, the high temperature and pressure in the air convert atmospheric nitrogen into oxides of nitrogen that can dissolve in water to produce nitric and nitrous acids. These fall along with rain. 

[2]. Certain forms of bacteria are able to convert atmospheric nitrogen into usable forms such as nitrates and nitrites. Such nitrogen fixing bacteria are commonly found in the roots of legumes (plants of pulses) inside special structures called root nodules.

These usable forms of nitrogen are absorbed by plants to produce many compounds such as amino acids, which in turn form proteins.

When an animal feeds on plants, nitrogen enters its body. 

Denitrification is the process in which certain bacteria convert nitrates and nitrites into molecular nitrogen (N2) form and is returned back to the atmosphere. In this way denitrifying bacteria contribute to nitrogen cycle.

@Swapnil, You friend has answered (a) and (b).

Hope you got it.

@ Mannu, Good effort. Keep it up!