What is the similarity/ difference between a molecule, diatomic molecule, and a molecular compound?

Balance this equation co2(g) + h2o (g) show that the balanced equation obeys the law if conversation of mass

Can someone me with questions 15 to 17 plz.

Liquid ammonia is produced at high temperatures and under great pressure in a tank by passing a mixture of nitrogen gas and hydrogen gas over an iron catalyst. the reaction is represented by the following equation. n2(g) + 3h2(g) → 2nh3(g) changing all but one experimental condition will affect the amount of ammonia produced. that condition is a) increasing the concentration of both reactants b) changing the temperature within the tank c) decreasing the pressure within the tank. d) increasing only the amount of nitrogen present.