If you have 20.0 g of co2, how many atoms of oxygen (o) are present in the sample?

20 g of CO₂ have 5.47x10²³ oxygen atoms

Explanation:

1 mol of CO₂ has 1 mol of C and 2 moles of O.

Mass / Molar mass = Moles

20 g / 44 g/m = 0.454 moles

In 1 mol we find 2 moles of O

In 0.454 moles of CO₂, we will find ( 0.454  .2) = 0.909 moles

1 mol has 6.02x10²³ atoms

0.909 moles have (0.909 .  6.02x10²³) = 5.47x10²³ atoms

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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.