Counting shared electrons in covalent bonds

Steps:

• Determine Lewis structure for each molecule to identify bonds.
• Count bonding pairs (each pair = 2 electrons in covalent bonds).
• Multiply bonding pairs by 2 for total shared electrons.
• Compare to find molecule with exactly 4 electrons.

Why C is correct:

• H₂S has two single bonds (H-S-H), so 2 bonding pairs × 2 = 4 shared electrons.

Why the others are wrong:

• A. Cl₂ has one single bond, so 1 bonding pair × 2 = 2 shared electrons.
• B. CO₂ has two double bonds (O=C=O), so 4 bonding pairs × 2 = 8 shared electrons.
• D. N₂ has one triple bond, so 3 bonding pairs × 2 = 6 shared electrons.

Final answer: C