Answer:
2.7099×10^19 molecules
Explanation:
At STP,
P = 1 atm = 101325N/m^2, T = 273K
From the ideal gas equation
PV = nRT
n = PV/RT
V = 1cm^3 = 1cm^3 × 1m^3/10^6cm^3 = 10^-6m^3, R = 8.31J/molK
n = 101325×10^-6/8.31×273 = 4.5×10^-5 mole
From Avogadro's law
1 mole = 6.022×10^23 molecules
4.5×10^-5 mole = 4.5×10^-5 × 6.022×10^23 = 2.7099×10^19 molecules
