Which process, in order, would be necessary for this sequence of the rock cycle: rock → metamorphic rock → igneous rock

Heat and pressure → melting → cooling

Weathering and erosion → compaction → weathering and erosion

Melting → cooling → melting → erosion

Cooling → melting → cooling → weathering and erosion

may be the answer is Heat and pressure - melting - cooling

explanation:

let the different atoms be x and y. each with four protons and same mass will be represented as follows.

mass number is number of protons + number of neutrons.

            and  

since, it is given that one has a negative charge while the other is neutral. therefore, there will be increase in number of protons and the atom will be represented as follows.

according to periodic table, mass number of beryllium is 9 and it has atomic number 4 so, the atoms will be and .  

the protons and neutrons will be located inside the nucleus whereas the electrons will be revolving around the nucleus.