Answer:
Ba(ClO₃)₂ → BaCl₂ + 3 O₂ Descomposition.
CaO + CO₂ → CaCO₃ Combination.
NaNO₂ + HCl → NaCl + HNO₂ Double replacement.
Mg + ZnSO₄ → MgSO₄ + Zn Single replacement.
Step-by-step explanation:
A combination reaction is defined as a reaction in which two or more substances combine to form a single new substance.
A + B → AB
A descomposition reaction is defined as a reaction in which a compound breaks down into two or more simpler substances.
AB → A + B
A double replacement is a chemical reaction were the positive and negative ions of two ionic compounds exchange places to form two new compounds.
AB + CD → AD + CB
A single replacement is another type of reaction were one element replaces a similar element in a compound.
A + BC → AC + B
Thus, with this information it is possible to classify these reactions as:
Ba(ClO₃)₂ → BaCl₂ + 3 O₂ Descomposition. One single molecule breaks down into two or more molecules
CaO + CO₂ → CaCO₃ Combination. Two substances are combined to form one single molecule
NaNO₂ + HCl → NaCl + HNO₂ Double replacement. Na and H are exchange places to form two new compounds
Mg + ZnSO₄ → MgSO₄ + Zn Single replacement. Mg is replacing Zn.
I hope it helps!