Answer:
CaC2 + 2H2O > C2H2 + Ca(OH)2
Step-by-step explanation:
Count the amounts of Ca, C, H, and O, all separately on both sides.
Ca: 1 Ca: 1
C: 2 C:2
H: 2 H: 4
O: 1 O: 2
Now, your goal is to get both sides equal to each other by adding a 2 in front of H2O.