CGPET 2018 Solved Paper

1. The given reaction is an Etard reaction, in which toluene reacts with chromyl chloride $(\mathrm{CrO}_2 \mathrm{Cl}_2)$, to give benzaldehyde. Hence, statement ( 1 ) is correct answer. 2. Nitration of benzene is an example of electrophilic substitution, in which $-\mathrm{NO}_2$ group is replaced by hydrogen atoms, attached to the ring. Hence, statement (2) is wrong. 3. $\mathrm{AlCl}_3$ is a strong Lewis acid, in Friedel-Craft reaction, it will keep the halide part away from the aromatic ring by making a complex $[\mathrm{AlCl}_3-X]$ Thus, the given statement is wrong. 4. Nitration of benzene is carried out by a mixture of $\mathrm{HNO}_3$ (conc.) and $\mathrm{H}_2\mathrm{SO}_4$ (conc.). (i) $\mathrm{H}_2\mathrm{SO}_4$ (conc.) $+\mathrm{HNO}_3$ (conc.)$\xrightarrow[\mathrm{H}_2\mathrm{NO}_3^+]{\cdot \mathrm{HSO}_4^{-}}$ (ii) $[\mathrm{H}_2\mathrm{NO}_3]^+ \rightarrow \mathrm{NO}_2^+ + \mathrm{H}_2\mathrm{O}$ In this reaction, $\mathrm{HNO}_3$ (conc.) behaves as a base. Thus, statement (iv) is correct. Hence, statements $(2)$ and $(3)$ are wrong. Therefore, option (b) is the correct answer.