Answer:
synthesis
Explanation:
Step 1: Data given
Decomposition = a reaction in which a compound breaks down into two or more simpler substances. The general form of a decomposition reaction is:
AB→A+B
Synthesis = A reaction that occurs when one or more compounds combines to form a complex compound:
A + B → AB
Double replacement: a reaction in which the positive and negative ions of two ionic compounds exchange places to form two new compounds.
The general form of a double-replacement reaction is:
AB+CD→AD+BC
Combustion reaction = a reaction in which a substance reacts with oxygen gas, releasing energy in the form of light and heat. Combustion reactions must involve O2 as one reactant.
single replacement = A reaction in which one element replaces a similar element in a compound. For example, a metal replaces an other metal.
The general form of a single-replacement (also called single-displacement) reaction is:
A+BC→AC+B
The reaction Na2O + H2O → 2NaOH
⇒ Does not involve O2 = NOT a combustion reaction
⇒ There is no replacement of 1 or more elements,.. This reaction is not a single replacement, neither a double replacement.
⇒ A compound does not break down into smaller substances = NOT a decomposition
The compounds starts from 2 simple substance to form a more compelx compound = a synthesis
