Question

Hydrogen gas (H2) and oxygen gas (O2) react to form liquid hydrogen peroxide (H2O2). Which statement is true about the reaction?

The product that is formed has the same physical properties as the reactants.

The atoms of the reactants have combined to form a new substance.

The same atoms are present, so the chemical properties are the same.

The two gases have mixed together, but a new substance has not formed.

Answer 1

When two substances react with one-another, it is by definition a chemical change. We can say that through no physical means can we get back H2 or O2, so we have a new substance altogether, meaning that the atoms of the reactants have combined to form a new substance is true (answer B).

Answer 2

The atoms of the reactants have combined to form a new substance.