Question

Assertion: Atmospheric nitrogen gas is always fixed by nitrogen -fixing micro-organisms.

Reason: Decomposers release nitrogen gas from dead bodies of plants and animals.

• A. Both assertion and reason are true and reason is the correct explanation of assertion
• B. Both assertion and reason are true but reason is not the correct explanation of assertion
• C. Assertion is true but reason is false
• D. Both assertion and reason are false

Answer 1

The correct option is D Both assertion and reason are false

Atmospheric nitrogen gas can be fixed by nitrogen -fixing micro-organisms (biological nitrogen fixation) and physical nitrogen fixation (fixation by lightining).

Decomposition is the process in which complex organic matters are broken down into inorganic substances like carbon dioxide, water and nutrients. Decomposition of organic nitrogen from dead plants and animals releases ammonia.
Denitrification is the process during which denitrifying bacteria breakdown nitrates and return nitrogen to atmosphere.