The speed of an object at a particular point during travel is called

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.

What is the increase in density of a medium due to wave travel?

How do you know how many valence electrons an atom has?