Final answer:
Nitrogenase is the enzyme used to generate reactive nitrogen species (RNS) in the process of nitrogen fixation. It contains iron and molybdenum and is found in microorganisms that have a symbiotic relationship with plants.
Step-by-step explanation:
An enzyme that is used to generate reactive nitrogen species is called nitrogenase. Nitrogenase is found in microorganisms and is involved in the process of nitrogen fixation, where atmospheric nitrogen is converted into biologically useful chemicals. Nitrogenase contains iron and molybdenum and plays a crucial role in the symbiotic relationship between microorganisms and plants.