'$$x$$' is the product which is obtained from benzene by reacting it with carbon monoxide and hydrogen chloride in the presence of cuprous chloride. '$$y$$' is the major product obtained from the benzene by reacting it with ethanoyl chloride in the presence of anhydrous AlCl$$_3$$. Product (major) obtained by heating $$x$$ and $$y$$ in the presence of alkali is $$z$$. Total number of $$\pi$$ (pi) electrons in $$z$$ is __________.

Benzene reacts with carbon monoxide and hydrogen chloride in the presence of cuprous chloride to give benzaldehyde by the Gattermann-Koch reaction.

$$x=C_6H_5OH$$

Benzene reacts with ethanoyl chloride $$(\mathrm{CH_3COCl})$$ in presence of anhydrous $$\mathrm{AlCl_3}$$​ to give acetophenone by Friedel-Crafts acylation.

$$y=C_{6}H_{5}COCH_3$$

On heating benzaldehyde and acetophenone in presence of alkali, Claisen-Schmidt condensation occurs to form chalcone:

Now count total $$\pi$$-electrons in Chalcone:

• Two benzene rings: 6+6=12
• One $$C=C$$ bond: 2
• One $$C=O$$ bond: 2

Total $$\pi$$ bonds is 16.