\(\begin{array}{l}
2NaHC{O_3} \to N{a_2}C{O_3} + C{O_2} + {H_2}O\\
BaC{O_3} \to BaO + C{O_2}\\
MgC{O_3} \to MgO + C{O_2}\\
= > X:N{a_2}C{O_3},MgO,BaO\\
Y:C{O_2},{H_2}O\\
BaO + {H_2}O \to Ba{(OH)_2}\\
Ba{(OH)_2} + N{a_2}C{O_3} \to BaC{O_3} + 2NaOH\\
= > A:NaOH,Ba{(OH)_2}\\
Z:BaC{O_3},MgO\\
Ba{(OH)_2} + C{O_2} \to BaC{O_3} + {H_2}O\\
BaC{O_3} + C{O_2} + {H_2}O \to Ba{(HC{O_3})_2}\\
= > B:BaC{O_3}\\
C:Ba{(HC{O_3})_2}\\
Ba{(HC{O_3})_2} + 2NaOH \to BaC{O_3} + N{a_2}C{O_3} + 2{H_2}O
\end{array}\)
