Ontario Grade 9 Science Class Practice Exam

What is a mixture?

1. Two or more molecules chemically joined together

2. A single type of atom

3. An object with more electrons than protons

4. A substance made up of at least two different types of particles

The correct answer is: A substance made up of at least two different types of particles

A mixture is a physical combination of at least two different types of particles. Option A is incorrect because it describes a chemical compound rather than a mixture. In a compound, two or more molecules are chemically bonded together, while in a mixture, the particles retain their individual properties. Option B is incorrect because it describes an element, which is a substance made up of only one type of atom. Option C is incorrect because it describes an object's net charge rather than its composition. A mixture can be made up of particles with varying numbers of electrons and protons. Option D is the best choice because it accurately defines a mixture as a combination of different particles without assuming their properties.