Answer:
15.2L at STP
Explanation:
Given reaction expression;
     CaCO₃ → CaO + CO₂
Number of moles of CaCO₃  = 0.68mol
Unknown:
Volume of COâ‚‚ produced at STP = ?
Solution:
To solve this problem, we must first find the number of moles COâ‚‚ produced,
   1 mole of CaCO₃ will produce 1 mole of CO₂
  0.68mole of CaCO₃ will produce 0.68mole of CO₂ at STP
Now;
       1 mole of gas occupies a volume of 22.4L at STP;
      0.68mole of CO₂ will then occupy 0.68 x 22.4  = 15.2L at STP
