Answer:
Assuming the question was about 3 mol CO2 - it's 132g. Assuming it's about CO - it's 84g.
Step-by-step explanation:
The molar mass of X means "a mole of X weighs that".
So 1 mol CO2 weighs 44g, so 3 moles will weigh three times that - 132g.
Now, with CO, we need to compute the molar mass of CO. One particle of CO is comprised of 2 atoms - a Carbon atom and an Oxygen atom, with molar masses ~12g and ~16g respectively. That brings us to molar mass of CO of 28g and the mass of 3 mol CO of 28g*3 = 84g