Which phrase describes how metamorphic rocks form? form from melting
form at Earth’s surface
form from sediments
form from existing rocks

since the atomic number is the number of protons in the nucleus, as we move to the left on the periodic table, the electrostatic pull between the nucleus and the valence electron shell decreases. as we move down a group (vertical column), the valence shell energy level gets further and further from the nucleus.

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