Q. Study the following table
Type Example Role
I) Sulphur Bacterium Thiobacillus thio-oxidans Oxidation of elemental sulphur
II) Nitrogen fixing Bacterium Nitrobacter Oxidation of nitrites
III) Iron Bacterium Thiobacillus thiooxidans Oxidation of Ferric salts to ferrous ions
IV) Hydrogen Bacterium Hydrogeno monas Oxidation of
The correct combination is

 42  189 NTA AbhyasNTA Abhyas 2020 Report Error

Solution:

Thiobacillus thioxidans are sulphur bacteria. This bacteria help in oxidation of elemental sulphur present in atmosphere. Biological Nitrogen fixation is done by converting N2 to Nitrates. This is done by first conversion of N2 to ammonia . Then ammonia is oxidised to nitrites and then nitrite oxidised to nitrates. Oxidation of nitrite to nitrates is stimulated by nitrobacter. Oxidation of H2 is done by hydrogen bacterium named hydrogenmonas. So 1,2and 4 are correct . 3 is wrong because thiobacillus thioxidans are sulphur bacteria not iron bacteria.