What are the independent and dependent variables?

characterization of nanoparticles is a critical step in nanomaterial production as it provides information of dimension, morphology, surface charge, distribution and degree of surface functionalization.

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.

what are the options? add them, then i will be glad to .