Avogadro's number is equal to?

Someone, 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.

In salt water solution,the salt is the blank

Can someone me with 3 and 4 plz. this is for masteries test.