Each water molecule is joined to other water molecules by bonds. each water molecule is joined to other water molecules by bonds. four polar covalent two hydrogen two polar covalent four hydrogen three ionic

  Each water molecule is joined to four other water molecules by hydrogen bonds.

Explanation:  As we know that the hydrogen bonding is a type of bonding in which the hydrogen attached to the electronegative atom of one molecule makes electrostatic forces of attraction with the electronegative atom of the other molecule.

Thus hydrogen which is attached to the electronegative oxygen atom will make a bond with the oxygen atom of the other molecule of water . Thus four types of binds can be formed with the one molecule of the water.

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.