For each set of numbered questions, there are five lettered choices. Select the one lettered choice that best fits each phrase, statement, equation, or formula. Alettered choice may be used once, more than once, or not at all. Questions 1—4 (A) melting
(B) sublimation
(C) condensation
(D) evaporation
(E) freezing
2. H20(s) H20(g)
3. C18H38(1) C18H38(s)
4. C2H5C1(1) —Y C2H5C1(g)

the reaction mixture contains some ammonia, plus a lot of unreacted nitrogen and hydrogen. the mixture is cooled and compressed, causing the ammonia gas to condense into a liquid. the liquefied ammonia is separated and removed. the unreacted nitrogen and hydrogen are then recycled back into the reactor .

the ideal gas law equation is as follows

pv = nrt

where p - pressure

v - volume

n - number of moles

r - universal gas constant

t - temperature

so if the pressure, volume and temperature are already known

we are left with n and r

since r is the universal gas constant that has a known fixed value then r too is known

so we are left with 'n'

once we know temperature volume and pressure

we can find the number of moles of gas present using the ideal gas law equation

this is not my own answer, this is an answer for the same question by the user blahblahmali. i do not claim ownership of this account.