Nwhich group are all the elements found naturally only in compounds?

Group 2

Explanation:

you must be referring to the groups in the periodic table. Well, the group that fits your question is group 2.

This is the group of alkaline earth metals. These elements have this name because they are usually found on earth. They are quite reactive, but less so than group 1 metals. They are also electropositive and are harder and denser than alkali metals. They are used in metal alloys as is the case for example of Beryllium (Be), in the composition of plaster and marble being the case of calcium (Ca) and in magnesium (Mg) and strontium (Sr) fireworks.

the correct answer is 4) heat and pressure

metamorphic rocks arise from transformation of existing rocks types, in a process called metamorphism. during metamorphism the original rock(prolith) change into metamorphic rock by heating (150-200c) and pressure of more than 1000 bar. the original rock can be sedimentary, igneous, or existing metamorphic rock.