Which weighs more, 0.50 mole oxygen atoms or 4 mole of hydrogen atoms?

0.5 moles of oxygen weighs more than that of the 4 moles of hydrogen.

Explanation:

Atomic mas of oxygen = 16.0 g/mol

mass of 0.50 moles of oxygen atom =

Atomic mas of hydrogen = 1.0 g/mol

Mass of 4 moles of hydrogen atom =

0.5 moles of oxygen weighs more than that of the 4 moles of hydrogen.

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.