When two carbon atoms are joined by a double bond, how many electron pairs are shared between the two carbons

Two (2) electron pairs

Explanation:

The sharing of electron pairs by atoms forms a type of bond called COVALENT bond. Atoms that form covalent bonding (share electrons) do so in order to fill their outermost electron shells, hence, gain chemical stability.

However, when two atoms like carbon share TWO PAIRS of electrons with each other, a DOUBLE BOND is formed. An example is the double bond formed in Ethylene (2HC=CH2). A total of four valence electrons (a pair from each carbon) are shared between the two carbon atoms.

the answer is definitely c.

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