' x ' is the product which is obtained from benzene by reacting it with carbon monoxide and hydrogen chloride in the presence of cuprous chloride. '…

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