Answer:
2.99 mol
Step-by-step explanation:
Number of moles of CO₂ = ?
Volume = 67 L
Temperature and pressure = standard
Solution:
The given problem will be solve by using general gas equation, 
PV = nRT 
P= Pressure 
V = volume 
n = number of moles 
R = general gas constant = 0.0821 atm.L/ mol.K 
T = temperature in kelvin
By putting values,
1 atm × 67 L = n ×0.0821 atm.L/ mol.K × 273.15 K
67 atm.L = n×22.43 atm.L/ mol
n = 67 atm.L/22.43 atm.L/ mol
n = 2.99 mol