Hey there!
CaCO₃ + HCl → CaCl₂ + CO₂ + H₂O
We have to balance Ca, C, O, Cl, and H.
Let's balance H.
One on the left, two on the right. Add a coefficient of 2 in front of HCl.
CaCO₃ + 2HCl → CaCl₂ + CO₂ + H₂O
Balance Ca.
One on the left, one on the right. Already balanced.
Balance C.
One on the left, one on the right. Already balanced.
Balance O.
Three on the left, three on the right. Already balanced.
Balance Cl.
Two on the left, two on the right. Already balanced.
Our final balanced equation:
CaCO₃ + 2HCl → CaCl₂ + CO₂ + H₂O
The answer is C. 1; 2; 1; 1; 1.
Hope this helps!
