Question

An aluminum patio chair reacts with the oxygen in the air. A layer of aluminum oxide forms on the chair. The formation of aluminum oxide is both an oxidation-reduction reaction and a _____ reaction.

A. single-replacement
B. combustion
C. decomposition
D. synthesis

Answer 1

D synthesis reaction

Single replacement will be like
Cl2 + 2NaBr —> 2NaCl + Br2
This is because only one element is moved from the reactants to the products (Cl)

Combustion will be like
CH4 + 2O2 —> 2H2O + CO2
Which involves oxygen gas

Decomposition is
NaCl —> Na + Cl
Where the compound breaks apart

And synthesis is
Na + Cl—> NaCl
Where a compound is made
Much like your problem
Al + O2 —> Al2O3 (aluminum oxide)