Total bonding electrons equal in paired molecules

Steps:

• Count covalent bonds in each molecule using Lewis structures.
• Multiply bonds by 2 to get shared electrons in covalent bonds.
• Compare totals within each pair for equality.
• Identify pair with matching bonding electron counts.

Why C is correct:

• NH₃ has three N-H single bonds (6 electrons); N₂ has one N≡N triple bond (6 electrons), matching by bond electron formula (2 electrons per bond).

Why the others are wrong:

• A: CH₃OH has 5 bonds (10 electrons); CH₃CH₂OH has 8 bonds (16 electrons).
• B: CO has 3 bonds (6 electrons); H₂O has 2 bonds (4 electrons).
• D: O₂ has 2 bonds (4 electrons); Cl₂ has 1 bond (2 electrons).

Final answer: C