Question

The acceptable resonating structures of the following molecule are:

\[\begin{array}{cc}
\ce{CH3 - CH = C - \overset{\bullet\bullet}{\underset{\bullet\bullet}{O}} - CH2 - CH3}\\
|\phantom{......}\\
\ce{:N}\phantom{.......}\\
\phantom{}/\phantom{...}\backslash\phantom{......}\\
\phantom{}\ce{H3C}\phantom{.....}\ce{CH3}\phantom{......}
\end{array}\]

(x)	\[\begin{array}{cc} \ce{CH3 - \overset{\overset{Θ}{\bullet\bullet}}{C}H - C -  \overset{\bullet\bullet}{\underset{\bullet\bullet}{O}} - CH2 - CH3}\\ ||\phantom{......}\\ \ce{N^⊕}\phantom{.....}\\ \phantom{}/\phantom{...}\backslash\phantom{......}\\ \phantom{}\ce{H3C}\phantom{.....}\ce{CH3}\phantom{......} \end{array}\]
(y)	\[\begin{array}{cc} \ce{CH3 - \overset{\overset{Θ}{\bullet\bullet}}{C}H - C =  \overset{⊕}{\underset{\bullet\bullet}{O}} - CH2 - CH3}\\ |\phantom{......}\\ \ce{:N}\phantom{.......}\\ \phantom{}/\phantom{...}\backslash\phantom{......}\\ \phantom{}\ce{H3C}\phantom{.....}\ce{CH3}\phantom{......} \end{array}\]
(z)	\[\begin{array}{cc} \ce{CH3 - \overset{⊕}{C}H - C -  \overset{\bullet\bullet}{\underset{\bullet\bullet}{O}} - CH2 - CH3}\\ ||\phantom{......}\\ \ce{N^Θ}\phantom{.....}\\ \phantom{}/\phantom{...}\backslash\phantom{......}\\ \phantom{}\ce{H3C}\phantom{.....}\ce{CH3}\phantom{......} \end{array}\]
(w)	\[\begin{array}{cc} \ce{CH3 - \overset{⊕}{C}H - C =  \overset{Θ}{O} - CH2 - CH3}\\ |\phantom{......}\\ \ce{:N}\phantom{.......}\\ \phantom{}/\phantom{...}\backslash\phantom{......}\\ \phantom{}\ce{H3C}\phantom{.....}\ce{CH3}\phantom{......} \end{array}\]

Options

• x, y

• x, z

• y, z

• z, w

Answer 1

x, y

Explanation:

Expansion of octet is not possible for the second-period element.

∴ z and w are not acceptable.