Physical process of nitrogen fixation
Answers
Answer:
Under the influence of lightning (i.e., electric discharge in the clouds) and thunder, N2 and O2 of the air react to form nitric oxide (NO). The nitric oxides are again oxidized with oxygen to form nitrogen peroxide (NO2).
The reactions are as follows:
N2 + O2 Lightning → Thunder 2N0 (Nitric Oxide); 2NO + O2 → 2NO2 Oxidation (Nitrogen peroxide)
During the rains, NO2 combines with rain water to form nitrous acid (HNO2) and nitric acid (HNO3). The acids fall on the soil along with rain water and react with the alkaline radicals to form water soluble nitrates (NO3-) and nitrites (N02-).
2NO2 + H2O → HNO2 + HNO3; HNO3 + Ca or K salts → Ca or K nitrates
The nitrates are soluble in water and are directly absorbed by the roots of the plants.
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Answer:
(1) Conversion of free nitrogen of air into nitrogenous compounds that are made available to plants for uptake is known as nitrogen fixation.
(2) Physical nitrogen fixation occurs in stepwise manner and it takes place in atmosphere and soil.
(3) Under the influence of electric discharge, lightning and thunder, atmospheric nitrogen combines with oxygen to form nitric oxide.
(4) Nitric oxide is then oxidized to nitrogen peroxide in presence of oxygen.
(5) Niirogen peroxide combines with rainwater to form nitrous and nitric acid which come on ground as acid rains.
(6) On ground, alkali radicals (mainly of Ca, K) react with nitric acid to produce nitrites and nitrates which are absorbable forms for plants.