Answer:
I'd say "a" because not everything with plants and animals is perfectly organized together nothing ever is.
There would be a 2 infront of the NH3 and and 2 Infront of the H2O
Since the exponent is negative, you move the decimal (2.0) to the left two spots leaving you with .02
Chemical properties can be determined by heat combustion, how they react with other chemicals, Oxidization (lose electrons, losing hydrogen, gaining oxygen), or toxicity.