If a scientific idea has been proven 100% of the time, like gravity, it becomes a whereas an idea that is generally believed but has not been proven to be 100% true would be called a .

The correct answer would be - scientific theory.

Explanation:

A scientific theory is a confirmed explanation of any particular natural aspect or phenomenon of the world which is confirmed and accepted widely by the facts based on observation and experiment.

This particular idea or explanation for the natural phenomenon is true time based and believed to be true for time being and proved for a time but can be changed with the new discoveries and facts.

step 1: nitrogen fixation- conversion of atmospheric no₂ into forms useful to plants by lightning, bacteria, and cyanobacteria.

step 2: nitrification-process of converting ammonia to nitrite or nitrate.

step 3: assimilation-plant roots absorb new form of nitrogen.

step 4: ammonification-conversion of organic nitrogen to ammonia by bacteria involved in decomposition.

step 5: denitrification-bacteria turns the decomposed matter back into n₂o, which is released into atmosphere; repeat cycle.