Answer:
Reflection involves a change in direction of waves when they bounce off a barrier. Refraction of waves involves a change in the direction of waves as they pass from one medium to another.
Answer:

Explanation:
Density can be found by dividing the mass by the volume.

The mass of the quartz is 30 grams and the volume is 6 cubic centimeters.

Substitute the values into the formula.

Divide.

The density of this piece of quartz is 5 grams per cubic centimeter.