What is a compound?
A.
a mixture of two or more elements that do not combine chemically
B.
a pure substance in which the atoms of three or more elements are chemically combined
C.
a mixture of two or more elements that retains the essential properties of each element
D.
a pure substance in which the atoms of two or more elements are chemically combined

C.

Explanation:

A compound is a thing that is composed of two or more separate elements; a mixture. Which is described in option C

i believe it is 40–40–20%

explanation:

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.