Which conclusion is best supported by julie’s observations? a. the liquid is a pure substance because it is colorless. b. the liquid is a mixture because its temperature rises. c. the liquid is a pure substance because it remains liquid when cold. d. the liquid is a mixture because it has a gas dissolved in a liquid.

Which of the following statements is true? a. most heat energy is easily recovered and used for useful actions. b. friction causes molecules to vibrate more slowly. burning air and gasoline in an c. engine changes chemical energy into mechanical energy. it is impossible to d. change mechanical energy into mechanical energy.