Final answer:
A combination reaction example is the formation of sodium chloride from sodium and chlorine, and a decomposition reaction example, using a catalyst, is hydrogen peroxide breaking down into water and oxygen with the help of manganese dioxide.
Step-by-step explanation:
An example of a combination reaction is the formation of sodium chloride from sodium and chlorine gas:
2 Na + Cl₂ → 2 NaCl
An example of a decomposition reaction where a catalyst is used is the decomposition of hydrogen peroxide (H₂O₂) into water (H₂O) and oxygen (O₂), which can be sped up by using manganese dioxide (MnO₂) as a catalyst:
2 H₂O₂ → 2 H₂O + O₂
In this example, manganese dioxide does not get consumed in the reaction and serves to lower the activation energy, allowing the reaction to proceed at a much faster rate.