Question

2H2 + O2 --> 2H2O can be classified as what type of reaction? A. Both synthesis and combustion. B. Only synthesis. C. Only combustion. D. It cannot be classified.

Answer 1

Two things reacting to form one product is a synthesis reaction.
So the answer is
A. Both synthesis and combustion.

Answer 2

The answer is B. Only synthesis.

Step-by-step explanation:

Synthesis reactions are those in which two substances combine, giving rise to new substances. Breakdown of chemical bonds in reagents and formation of other bonds occurs, giving rise to new species.

A combustion is any reaction created between the combustible material and the oxidizer. Oxygen has the ability to combine with various elements to produce oxides. There are oxidations that are extremely slow, but when it is fast it is called combustion. That is why the oxidizer is oxygen, and the fuel is usually hydrocarbons (organic compounds made up of only carbon and hydrogen atoms). These usually go into combustion with ease.

In this case it is a synthesis, where two reagents,
`H_(2)` and
`O_(2)`, are combined to form a product,
`H_(2) O`. It is not a combustion because despite having
`O_(2)` there is no hydrocarbon.