Which rock is only formed by regional metamorphism?

Metamorphism, which takes place over the wide regions of the crust is known as regional metamorphism. The majority of the regionally metamorphosed rocks takes place in the regions, which have gone through deformation at the time of an orogenic event.  

Gneiss is only produced by regional metamorphism. Gneiss can be produced by the regional metamorphism of distinct kinds of rocks like shale or granite. It refers to a high-grade metamorphic rock, which signifies that it is produced at high pressures and temperatures.  

false

because it does not have the potential to be entirely used up

alkaline metals are lithium, sodium, rubidium, potassium, cesium and francium.

alkali metals have electronegativity from 0.7 to 1, lowest in periodic table of elements, which means that alkali metals (i group in periodic table) has positive oxidation number in compounds.

electronegativity is a chemical property that describes the tendency of an atom to attract a shared pair of electrons towards itself.

alkaline metals (far left in main group) have lowest ionizations energy and easy remove valence electrons,

for example, potassium is the alkali metal and has a single valence electron in the outer electron shell.

electron configuration of potassium is: ₁₉k 1s²2s²2p⁶3s²3p⁶4s¹.

they can not exist alone in nature, because they are very reactive.