What happens when the pressure of system is decreased?

In manufacturing of ammonia, What if the pressure of the system is decreased?

What happens to the pressure when the volume is decreased ?

Observe the figure and answer the questions. b) What happen when partial pressure of oxygen be comes same in the alveoli and alveolar capillary?

What happens when Na is dropped in water

What happens when the potentiometer wire Is replaced with a copper wire?

What happens when Borax is heated

What happens to the volume of the gas when its pressure is decreased or temperature is increased. Volume increased/ decreased ?