Consider the following sequence of reactions: Ethylbenzene [ (ii) H ₃ O ^+] (i) KMnO ₄ , KOH, P SOCl ₂ Q H ₂ , Pd/BaSO ₄ R The total number of hydrogen atoms in one molecule of the final product R is _______.

Step-by-step solution

(i) Ethylbenzene undergoes side-chain oxidation with alkaline KMnO ₄ followed by acidification to form benzoic acid (Compound P). (ii) Benzoic acid reacts with SOCl ₂ to form benzoyl chloride (Compound Q). (iii) Benzoyl chloride undergoes Rosenmund reduction with H ₂ and Pd/BaSO ₄ to form benzaldehyde (Compound R). The chemical formula of benzaldehyde is C ₆ H ₅ CHO (or C ₇ H ₆ O ). Therefore, the total number of hydrogen atoms in one molecule of R is 5 + 1 = 6 . Answer: 6