Answer:
[tex]\boxed{\text{ B. Increase the temperature and decrease the pressure.}}[/tex]
Explanation:
Let's say the reaction is
R ⇌ 2P; endothermic
I like to consider heat as if it were a reactant or a product in a chemical equilibrium.
Another way to write the equilibrium would be
heat + R ⇌ 2P
According to Le Châtelier's Principle, when a stress is applied to a system at equilibrium, the system will respond in a way that tends to relieve the stress.
Let's consider each of the stresses in turn.
(i) Changing the temperature
If you want to increase the amount of product, you increase the temperature. The system will try to get rid of the added heat by shifting to the right, thus forming more product.
(ii) Changing the pressure
If R and P are liquids or solids or in aqueous solution, changing the pressure will have no effect. Something must be in the gas phase for a change in pressure to affect the position of equilibrium.
If P is a gas, the equilibrium is
heat + R ⇌ 2P(g)
Then, decreasing the pressure will produce more P. If you reduce the pressure, the system will respond by shifting to the right (the side with more gas molecules) to produce more P and bring the pressure back up
