Look at the DNA molecule shown at right. What does it look like?

1.  An apple is something that has matter.

2. Light does not have matter. It neither has mass or takes up and space.

3. Physical changes only change the appearance of a substance, not its chemical composition. Chemical changes cause a substance to change into an entirely substance with a new chemical formula. Chemical changes are also known as chemical reactions.

4. A chemical reaction is usually accompanied by easily observed physical effects, such as the emission of heat and light, the formation of a precipitate, the evolution of gas, or a color change. Absolute confirmation of a chemical change can only be validated by chemical analysis of the products!

5. A precipitate is a solid that forms out of solution.

6. In simple terms, the endothermic reactions absorb energy from the surrounding that is in the form of heat. On the other hand, an exothermic reaction releases energy into the surrounding of the system.

Explanation:

Matter is anything that has mass and takes up volume.