Melting, freezing, and boiling are changes. question 3 options: a. compound
b. molecular
c. isotope
d. physical
e. chemical

Anne applies a force on a toy car and makes it move forward. what can be said about the forces acting on the toy car at the moment anne applies the force?

Which sentences describe disadvantages of burning fossil fuels instead of using hydrogen fuel cells? burning fossil fuels contributes to climate change. burning fossil fuels takes place inside expensive fuel cells. fossil fuels aren't widely available, but pure hydrogen is. fossil fuels are nonrenewable.

Ammonia enters the expansion valve of a refrigeration system at a pressure of 10 bar and a temperature of 18oc and exits at 6.0 bar. the refrigerant undergoes a throttling process. determine the temperature, in oc, and the quality of the refrigerant at the exit of the expansion valve.