Question

2H2 + O2 --> 2H2O can be classified as what type of reaction?

Answer 1

Combustion reaction
Key: O2
O2 is normally in a chemical formula when you are used to burn anything, so basically, anything with O2 involves burning.

Answer 2

It's Synthesis Reaction
A+B---->C

Combustion reaction produces carbon dioxide and water. This equation doesn't contain CO2