What is a main difference between a mixture and a pure substance? a A mixture is only a liquid, but a pure substance can be in any state. b A mixture can vary in composition, but a pure substance has a set composition. c A mixture can be made up of a single compound, but a pure substance cannot. d A mixture looks the same throughout, but a pure substance does not.

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Two kilograms of air within a piston–cylinder assembly executes a carnot power cycle with maximum and minimum temperatures of 800 k and 300 k, respectively. the heat transfer to the air during the isothermal expansion is 60 kj. at the end of the isothermal expansion the volume is 0.4 m3. assume the ideal gas model for the air. determine the thermal efficiency, the volume at the beginning of the isothermal expansion, in m3, and the work during the adiabatic expansion, in kj.

What energy transformations occur each time the skateboarder rolls up the ramp?