At STP, which gas sample has the same number of molecules as 2.0 liters of CH4(g) at STP?

January 2019 NY Regents Chemistry Exam

18 At STP, which gas sample has the same number of molecules as 2.0 liters of CH4(g) at STP?
(1) 1.0 liter of C2H6(g)

(2) 2.0 liters of O2(g)

(3) 5.0 liters of N2(g)

(4) 6.0 liters of CO2(g)

Solution: Gases with the same pressure, temperature and volume have the same number of molecules

Answer: 2

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