Which sample of argon gas has the same number of atoms as a 100.-milliliter sample of helium gas at

NY Regents Chemistry Exam June 2022

17 Which sample of argon gas has the same number of atoms as a 100.-milliliter sample of helium gas at 1.0 atm and 300. K? (1) 50. mL at 1.0 atm and 300. K

(2) 50. mL at 0.5 atm and 300. K

(3) 100. mL at 0.5 atm and 300. K

(4) 100. mL at 1.0 atm and 300. K

Explanation: When the temperature, pressure and volume is the same, the number of moles will be the same too according to the ideal gas law: PV=nRT

Answer: 4