Answer:
Four abiotic forms of nitrogen cycle and its chemical formula
Ammonium – 
Ammonia – 
Nitrite –
Nitrate – 
Explanation:
Ammonium: In the nitrogen cycle ammonium is starting point that is present in soil and are converted to various forms by different process.
Ammonia: In the process of nitrogen fixation, the bacteria having nitrogenase enzymes reacts with the nitrogen as well as hydrogen and produces the ammonia, which is further converted to organic compounds.
Nitrite: The nitrosomonas bacteria present helps in conversion of nitrogen gas into nitrite.
Nitrate: Again the Nitrite is converted into Nitrate by the nitrobacter. During the process of assimilation ammonium and nitrate are absorbed by the plants.
An inference draws conclusions based on evidence gathered through observation. The conclusion is reached logically on the basis of facts known to be true or assumed to be true. An inference can be seen as an interpretation of what is observed. An inference is an element of reasoning, an act of thinking.
During the process of ossification, an existing tissue is replaced by bone.
They drill holes and bring up samples of rock and study how seismic wave move through the earth.