PLZ HELP I DONT WANNA FAIL CHEM

In which reaction is precipitation occurring?

(04.05 hc) analyze the given diagram of the carbon cycle below. part 1: which compound does c represent? part 2: name a process that could release this compound into the air. part 3: explain how the elements that form it are conserved during the carbon cycle. use complete sentences to explain your answer. justify how this compound was created from a recycling of carbon in the carbon cycle. use complete sentences to explain your answer.

What the blanks in these lines are ?