Answer:
Ionic compound.
Explanation:
812° C is a very high melting point. Such high melting points are generally ionic compound. Ionic compounds are have very strong bond between the elements ( electrostatic bond). In order to break this bond, large amount of heat energies are needed. So, they have high melting point. Also, Ionic compound are very good conductors of electricity.
Answer:
Mass is the quantity of matter contained in a body. The mass of an object is measured in kilogram (kg).
Explanation:
1 atm corresponds to 760 mmHg, so we can set up a simple proportion to find how many atmospheres correspond to 570 mmHg:

and from this, we find
A. True
if cold air is replacing warm air it is a cold front and vice versa.