Which will diffuse faster CO2 or CO?

CO (carbon monoxide) will diffuse faster than CO2 (carbon dioxide) because it has a lower molar mass. According to Graham's law of effusion, lighter gases diffuse more quickly than heavier gases. Since CO has a molar mass of about 28 g/mol, while CO2 has a molar mass of about 44 g/mol, CO will diffuse more rapidly in a given environment.