Which of the following is always true when a substance undergoes a physical change a.) the composition changes b.) a change in color occurs c.) no new substance is formed d.) it's specific gravity remains the same

Why does the sun appear to be the brightest star in the sky? a- its apparent brightness is much greater than other stars. b- it burns more gas, making it brighter than any other star. c- it is the largest star in the galaxy, so it is the brightest star. d- its relative distance to earth is closer than the other stars.

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

George is a dalmatian puppy. describe what happens to light that allows you to see george’s black and white coat.