Helpp! based on the definitions above, identify each of the following as biotic (B) or abiotic (A)

the sand in the desert __

the bacteria in a lake __

pollen from a plant __

pollution from an oil refinery __

What type of reaction is zn + cucl2 → cu + zncl2?

Ineed ! i have no clue how to do this problem.

Nitric acid can be formed in two steps from the atmospheric gases nitrogen and oxygen, plus hydrogen prepared by reforming natural gas. in the first step, nitrogen and hydrogen react to form ammonia: (g) (g) (g) in the second step, ammonia and oxygen react to form nitric acid and water: (g) (g) (g) (g) calculate the net change in enthalpy for the formation of one mole of nitric acid from nitrogen, hydrogen and oxygen from these reactions. round your answer to the nearest .