Four people make observations recorded in the table. Which best describes what the observations have in common?

They involve nuclear energy.
They involve radiant energy.
They involve changes in waves.
They involve changes in energy.

Which substances have the lowest melting points: ionic covalent, or metallic

What forms when chemical reactions combine pollution with sunlight?

Transportation is the largest single source of air pollution in the united states. air pollution can harm the environment and human health. which technology could offer a solution to this problem? mufflers that reduce noise motors that run on electricity tires that improve gas mileage