Which is a substance that is made up of only one type of atom?

Joan writes four numbers on the board in standard form, and then she writes their scientific notation

Ajet plane is speeding down the runway during takeoff. air resistance is not negligible. identify the forces on the jet.

Which of the following is a physical change? a.burning a piece of wood b.sawing a piece of wood in half c.rust forming on an iron fence d.a copper roof changing color from orange to green