Explain why are hydrogen and oxygen considered as wheares water as a compound?

Amixture of gaseous sulfur dioxide and oxygen are added to a reaction vessel and heated to 1000 k where they react to form so3(g). if the vessel contains 0.669 atm so2(g), 0.395 atm o2(g), and 0.0851 atm so3(g) after the system has reached equilibrium, what is the equilibrium constant kp for the reaction: 2 so2(g) o2(g) ⇌ 2 so3(g)

What is the maximum number of electrons that an atomic orbital can contain?

Can someone me with questions 12 and 13 plz.