Question

multiple - choice question
2k + mgo ---> mg + k₂o
this is a ______ reaction.
combustion
synthesis
decomposition
single replacement
double replacement

Explanation:

• Combustion reaction: Involves reaction with oxygen to produce heat and light, usually with a hydrocarbon. This equation doesn't fit as there's no oxygen as a reactant in that sense.
• Synthesis reaction: Combines two or more reactants to form one product. Here, there are two products ($Mg$ and $K_2O$), so it's not a synthesis.
• Decomposition reaction: One reactant breaks down into two or more products. Here, there are two reactants ($2K$ and $MgO$), so it's not decomposition.
• Single - replacement reaction: A single element replaces another element in a compound. In $2K+MgO

ightarrow Mg + K_2O$, potassium ($K$) replaces magnesium ($Mg$) in magnesium oxide ($MgO$).

• Double - replacement reaction: Two compounds exchange ions. This is not the case here as it's an element - compound reaction.

Answer:

single replacement