Question 9 of 42
1 point
which of the following do scientists use to form a hypothesis?

a. a conclusion and data

b. a question and observations

c. a question and opinions
d. a conclusion and a theory

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.