How is a pure substance different than a mixture

Who is better, messi or cristiano, i need this for a chemistry class. asap

Asample of neon occupies a volume of 375 ml at stp. what will be the volume of neon if the pressure is reduced to 90.0 kpa? a. 422 ml b. 422 l c. 333 ml d. 333 l

The tilt of the earth's axis of rotation is responsible for the a) ocean's tides. b) size of the moon. c) brightness of stars. d) earth’s seasons.