12. What do we call the different substances that can be seen in a heterogeneous mixture?

chemical substances

Explanation:

A heterogeneous mixture is a mixture of two or more chemical substances where the various components can be visually distinguished. A homogeneous mixture is a type of mixture in which the composition is uniform and every part of the solution has the same properties.

answer: the metamorphic rocks are formed when they are exposed to high pressure and high temperatures. this happens when one of the earth's plates comes in contact with the other plate by traveling in opposite directions, straight into each other or slipping under one another. the friction that is caused by this activity results in   melting of rocks and when it cools they are known as metamorphic rocks. this process needs a controlled amount of pressure and temperature otherwise it may turn into magma.