Lone pairs on central atom in Lewis structures

Steps:

• Calculate total valence electrons for each species.
• Account for bonds: each single bond uses 2 electrons per atom.
• Check for non-bonding pairs on carbon after bonding.
• Identify species with at least one lone pair on carbon.

Why C is correct:

• CH₃⁻ has 8 valence electrons around carbon (4 from C + 3×1 from H +1 from charge); three C-H bonds use 6 electrons, leaving 2 as a lone pair.

Why the others are wrong:

• A. CH₄: 8 valence electrons form four C-H bonds, using all electrons with no lone pairs.
• B. CH₃⁺: 6 valence electrons form three C-H bonds, using all with no lone pairs.
• D. CH₂: 6 valence electrons form two C-H bonds (4 electrons), leaving 2 as unpaired electrons, not a lone pair.

Final answer: C