What do these organic compounds have in common?

methane (CH4 )

butane (C4H10)

They contain both carbon and hydrogen.

They contain only carbon.

They contain only hydrogen.

Which of the following is a testable hypothesis? a. if i brush my teeth, i will get fewer cavities than if i don't brush my teeth. b. green toothpaste tastes better than blue toothpaste or red toothpaste. c. smart, careful, healthy people always brush their teeth. d. it's wrong to not brush your teeth before you have an important conversation with someone.

Balance the following reaction. as2s3 + 9o2 → 2as2o3 + so2

Calculate the mass of 0.750 mol of the following substance. na3po4. , i'm not quite sure on how to set up the problem to solve! : (