Question

The nitrogen molecules present in the air can be converted into nitrates and nitrites by

विकल्प

• a biological process of nitrogen-fixing bacteria present in the soil

• a biological process of carbon fixing factor present in the soil

• any of the industries manufacturing nitrogenous compounds

• the plants used as cereal crops in the field

Answer 1

a biological process of nitrogen-fixing bacteria present in the soil

Explanation:

Nitrogen molecules present in the air cannot be used as such by plants and animals and must be converted into biologically 5 acceptable forms. A number of symbiotic and free-living bacteria e.g., Rhizobium, Azotobacter etc. convert nitrogen into ammonia. Most of the ammonium compounds are oxidised by nitrite bacteria (Nitrosomonas and Nitrosococcus) to soluble nitrates, which are further oxidised by nitrate bacteria (Nitrobacter and Nitrocystis) to soluble nitrates.