Ethene's Dot-Cross Diagram Shows C=C Double Bond

Steps:

• Ethene formula is C₂H₄, with two carbon atoms forming a double bond.
• Each carbon shares four valence electrons: two pairs with the other carbon, one pair each with two hydrogens.
• Diagram must display four shared electron pairs total, with crosses/dots distinguishing bonds.
• Verify by counting electrons: each C has 4, each H has 1, all paired in bonds.

Why B is correct:

• B depicts the C=C double bond as two shared electron pairs between carbons, satisfying the octet rule for each carbon (four bonds total).

Why the others are wrong:

• A shows a single C-C bond, resembling ethane (C₂H₆) instead of ethene's double bond.
• C displays a triple C-C bond, which would be ethyne (C₂H₂), not ethene.
• D incorrectly shows uneven electron sharing, violating the octet rule for carbon.

Final answer: B