How does a substance change at its melting point and at its boiling point?

This is when they become a liquid. So the melting point is the temperature at which molecules in a solid can move past each other and form a liquid. The boiling point, on the other hand, involves liquids and gases. ... As temperature is increased, the liquid molecules move faster and faster and more of them escape as gas.

At melting point a substance changes from solid to liquid staye and on boiling point liquid substance changes to gaseous state

Explanation:

answer: any goods being imported from another country may be subject to issued by the federal government are tariffs

explanation:  

tariffs are a tax on anything that are imported from abroad. government use them to protect and boost their local industries and the thought is that they encourage consumers to buy local instead of importing and they will hope will protect jobs and economy in the country that implements them