Question

A 2.0 L volume of hydrogen gas is combined with 1.0 L of oxygen gas to produce 2.0 L of water vapor. Does oxygen undergo a chemical or physical change? Explain

Answer 1

The properties like shape, structure, etc. that define the appearance of matter is said to be its physical properties whereas the properties like oxidation, toxicity, etc. that defines how a new product is formed from the other substances is said to be its chemical properties.

It is given that a 2.0 L volume of hydrogen gas is combined with 1.0 L of oxygen gas to produce 2.0 L of water vapor.  The chemical reaction is as:

$H_2(g) + O_2(g) \rightarrow H_2O(g)$

Since, the reaction between hydrogen and oxygen results in the formation of  complete new product, water. So, oxygen will undergo a chemical change.