Aldehydes, Ketones and Carboxylic Acids

'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 AlCl3. Product (major) obtained by heating x and y in the presence of alkali is z. Total number of π (pi) electrons in z is .

Consider the following reaction of benzene. [figure] In compound (Q), the percentage of oxygen is %. (Nearest integer)