What makes an element more metallic than another?

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

Why does a plastic bottle that is sealed at a high altitude change it’s shape when taken to lower altitude

Ab c or d ? i’m not sure what the answer is