Which of the following is a correct resonance structure for compound A, where compound A is ${\mathrm{CH}}_2=\mathrm{CH}-OH$?

• A. ${\mathrm{CH}}_2=\mathrm{CH}-O{+}^{}H$
• B. ${\mathrm{CH}}_2-\mathrm{CH}=O-H$
• C. ${\mathrm{CH}}_3-\mathrm{CH}=O$
• D. ${\mathrm{CH}}_2=\mathrm{CH}-O{-}^{}H$

Answer: (B)

Verified step by step guidance

1. Identify the structure of compound A, which is \( \mathrm{CH_2=CH-OH} \), known as vinyl alcohol.
2. Recall that resonance structures involve the delocalization of electrons, typically through the movement of pi electrons and lone pairs, without changing the positions of atoms.
3. Consider the possible resonance forms by moving the pi electrons of the C=C double bond toward the oxygen atom, which can accept electron density due to its electronegativity and lone pairs.
4. Draw the resonance structure where the double bond shifts from between the two carbons to between the carbon and oxygen, resulting in \( \mathrm{CH_2-CH=O} \) (an aldehyde form), while keeping the hydrogen attached to oxygen or carbon as appropriate.
5. Verify that the resonance structure obeys the rules: the octet rule is satisfied for all atoms, formal charges are minimized, and the overall charge of the molecule remains the same.