The combining of one substance with another which yields a different product is the result of a(n) physical change chemical change phase change exothermic change

It would be a chemical change. This is because when you combine two mixtures, or in your case, substances, the product will be different each time, as long as there are various ways to define the substances.

Option (b) is the correct answer.

Explanation:

A change that does not lead to any difference in chemical composition of a substance is known as a physical change.

For example, shape, size, mass, volume, density, boiling point, etc of a substance are all physical properties.

On the other hand, changes that lead to bring change in chemical composition of a substance is known as a chemical change.

For example, exploding dynamite, rotting cheese etc are all chemical changes.

A chemical change will always lead to the formation of a new product.

Whereas if state of a substance is changing from solid to liquid or liquid to gas etc then it is known as a phase change.

Thus, we can conclude that the combining of one substance with another which yields a different product is the result of a chemical change.

2h2o2--> 2h2o + o2

this reaction is of the spontaneous decomposition of hydrogen peroxide down into water and oxygen.

add 2 molecules of hydrogen peroxide and 2 molecules of water. since oxygen is naturally diatomic, the total number of atoms of each element is now the same on both sides of the equation so it is balanced.

this may not be entirely correct but let me know.