Total Pi Electrons and Lone Pairs in Product X

To determine the total number of electrons in the $\pi$ bonds and lone pairs of electrons in the major product $(X)$, we analyze the reaction sequence step-by-step:

Step 1: Reaction of Glucose with $\text{HI}, \Delta$

Prolonged heating of glucose with hydroiodic acid ($\text{HI}$) reduces all hydroxyl and carbonyl groups to form $n$-hexane: $\begin{array}{c} \text{CHO} \\ \mid \\ (\text{CHOH})_4 \\ \mid \\ \text{CH}_2\text{OH} \end{array} \xrightarrow{\text{HI}, \Delta} \text{CH}_3-\text{CH}_2-\text{CH}_2-\text{CH}_2-\text{CH}_2-\text{CH}_3 \quad (n\text{-hexane})$

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Step 2: Aromatization of $n$-hexane

Heating $n$-hexane at $773\text{ K}$ and $10\text{-}20\text{ atm}$ pressure in the presence of $\text{V}_2\text{O}_5$ catalyst undergoes cyclization and dehydrogenation (aromatization) to yield benzene: $\text{CH}_3(\text{CH}_2)_4\text{CH}_3 \xrightarrow[\text{10-20 atm, 773 K}]{\text{V}_2\text{O}_5} \text{C}_6\text{H}_6 \quad (\text{Benzene})$

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Step 3: Friedel-Crafts Acylation

Benzene reacts with benzoyl chloride ($\text{C}_6\text{H}_5\text{COCl}$) in the presence of anhydrous $\text{AlCl}_3$ to undergo electrophilic aromatic substitution, yielding benzophenone as the major product $(X)$: $\text{C}_6\text{H}_6 + \text{C}_6\text{H}_5\text{COCl} \xrightarrow{\text{Anhyd. AlCl}_3} \text{C}_6\text{H}_5-\overset{\begin{array}{c}\text{:O:}\\[-1ex]\parallel\end{array}}{\text{C}}-\text{C}_6\text{H}_5 \quad (\text{Benzophenone, } X)$

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Step 4: Counting $\pi$ electrons and lone pair electrons in Benzophenone $(X)$

1. Number of $\pi$ electrons:

   • Each benzene ring contains $3$ $\pi$ bonds ($6$ $\pi$ electrons). For 2 benzene rings: $2 \times 6 = 12$ $\pi$ electrons.
   • The carbonyl group ($\text{C}=\text{O}$) contains $1$ $\pi$ bond ($2$ $\pi$ electrons).
   • Total $\pi$ electrons $= 12 + 2 = 14$ $\pi$ electrons.

2. Number of lone pair electrons:

   • The oxygen atom in the carbonyl group possesses $2$ lone pairs.
   • Total lone pair electrons $= 2 \times 2 = 4$ electrons.

3. Total number of electrons: $\text{Total electrons} = \text{Total } \pi \text{ electrons} + \text{Total lone pair electrons} = 14 + 4 = 18$

Thus, the correct option is D (18).