Explanaton:
We have to determine the number of moles of a sample that has a volume of 1250.0 L at STP. STP means standard conditins of temperature and pressure.
We know that 1 mol of a gas at STP occupiesa volume of 22.54 L.
22.4 L = 1mol of gas
We can use that relationship to find the answer to our problem.
n° of moles 21250.0 L * 1 mol/(22.4 L)
n° of mles = 55.80 moles
Answer: there are 55.80 moles of gas in the sample.