An element playing important role in nitrogen fixation is?

The correct option is B

molybdenum

The correct option is B.

Explanation of correct option:

1. Plants can not use atmospheric nitrogen directly. They have to be converted into usable forms.
2. The conversion of molecular forms of nitrogen into nitrites and nitrates which can be used by plants is called nitrogen fixation.
3. This process can occur through lightning, biological, or industrial processes.
4. Molybdenum (Mo) is an essential micronutrient for plant growth that is required for the metabolism of nitrogen and the synthesis of proteins.
5. It acts as a co-factor that helps nitrogenase enzymes for catalyzing redox reactions for the conversion of elemental nitrogen from the atmosphere into usable ammonium ions.

Explanation of incorrect option:

Option A:

Zinc is a micronutrient that helps in chlorophyll and carbohydrates formation, withstand low temperatures, stem elongation, regulation of growth, and formation of sugars from starch.

Option C:

Copper is a micronutrient that helps in various enzymatic activities, and seed and chlorophyll production.

Option D:

Manganese is involved in respiration, nitrogen assimilation, photosynthesis, growth and germination of the pollen tube, pathogen resistance, and elongation of root cells.

Final answer: An element playing important role in nitrogen fixation is molybdenum.