Choose the sources of heat which create metamorphic rocks?

Hot molten rock called magma and geothermal heat

Explanation: Metarmorphic Rock are formed from the break down of existing igneous and sedimentary rock as a result of the intrusion of magma and high pressure which brings about a change in the physical and chemical nature of the rock into a denser form called metarmorphic Rock. Also, it is formed as a result of geothermal heat and friction along the fault.

the relative atomic mass of an element is the mass of one atom of that element, relative to 1/12th of the mass of a  1212c atom. to convert to an absolute mass in kg, it is necessary to multiply by  1.661×10−271.661×10−27.

the relative atomic mass is roughly equal to the number of neutrons, plus the number of protons, in the nucleus of the atom.

for elements with more than one stable isotope (different types of nucleus with different numbers of neutrons but the same number of protons), the quoted mass is usually the average mass, weighted by the relative abundance of the different isotopes.