12. If the pressure on the equilibrium system 2CO(g) + O2(g) = 2CO2(g) is increased, the quantity of CO(g) increases.
b. the quantity of CO2(g) decreases.
the quantity of CO2(g) increases.
d. the quantities in the system do not change.

a boiling water reactor does not boil the water. a pressurized water reactor boils the water faster. a pressurized water reactor is heated directly by the core. a pressurized water reactor does not use fission.

answer : a model is often used to explain and make things easier to understand when any scientific topic needs to be demonstrated and explained.

as in this case where a scientist wants to use a model to present the results of his detailed scientific investigation. he should do it as it will him to make the audience understand the concept in a much better way. also, it can be changed according to new scientific understandings.

i belive it is water