Types of Reaction

Decomposition

it is a form of reaction whereby a compound is broken into two or more small compounds, it can be thermally done.
CuCO_3(s)  →  CaCO(s) + CO_2(g)

Substitution

It is a form of reaction whereby an atom or group of atoms is replaced by another atom on group atoms. It is also farmed displacement reaction.
CaCO_3(s) + Zn(s)  →   ZnCO_3(s) + CO_(s)

Combination

It is a form of reaction whereby atoms of elements combine to form a compound
N_2(g) + 3H_2(g)  →  2NH_3(aq)

Double decomposition

It is a form of reaction between two soluble salts with the Intention of forming one soluble and one insoluble salt.
NaCL_(aq) + AgNO_3(aq) →  NaNO_3(aq) + AgCL_(s)

Reversible reactions

These are reactions which can proceed both In forward and backward directions. A+D  ⇌  C + D

Catalytic reaction

These are those reactions that utilize catalyst in it.
MnO2
2KCLO_3(g)  →    2KCL_(aq) + 3O_2(g)