How many stars are thete in universe ​

Explain how plate tectonics have changed earth’s surface over time. include the role of plate tectonics in the creation of landforms.

Which changes of state do the labels represent? a: b: c:

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.