For example, they can be harmful if taken in ... Open windows and turn on vent fans whenever possible. Pesticides are chemical substances used to prevent, repel, or kill pests.

An element is a substance that is made up of only ... a name for the element that is not an English word. For example, Lead is a chemical element with the symbol Pb (from the Latin for lead ...

The film explains the concept of chemical changes, where two or more materials combine to form entirely different substances. It highlights everyday examples of chemical changes, such as burning wood ...