The function of anhydrous ${\mathrm{AlCl}}_3$ in the Friedel Craft's reaction is :

Directions: Each of these questions contain an assertion followed by reason. Read them carefully and answer the question on the basis of the following options. You have to select the one that best describes the two statements.

Assertion: Rates of nitration of benzene and hexadeuterobenzene are different.
Reason: $\mathrm{C}-\mathrm{H}$ bond is stronger than $\mathrm{C}-\mathrm{D}$ bond.

Directions: Each of these questions contain an assertion followed by reason. Read them carefully and answer the question on the basis of the following options. You have to select the one that best describes the two statements.

Assertion: Benzene reacts with chlorine in the presence of bright light to form an insecticide $\mathrm{BHC}$ or gammexane.

Reason: In the formation of gammexane, benzene undergoes an aromatic electrophilic substitution.

Directions: Each of these questions contain an assertion followed by reason. Read them carefully and answer the question on the basis of the following options. You have to select the one that best describes the two statements.

Assertion: $p-{\mathrm{O}}_2\mathrm{N}-{\mathrm{C}}_6{\mathrm{H}}_4{\mathrm{COCH}}_3$ is prepared by Friedel-Crafts's acylation of nitrobenzene.

Reason: Nitrobenzene easily undergoes electrophilic substitution reaction.

Directions: Each of these questions contain an assertion followed by reason. Read them carefully and answer the question on the basis of the following options. You have to select the one that best describes the two statements.

Assertion: Friedel-Craft's reaction is used to introduce an alkyl or acyl group in benzene nucleus.

Reason: Benzene is an appropriate solvent for the Fridel-Craft's alkylation of bromobenzene.

Directions: Each of these questions contain an assertion followed by reason. Read them carefully and answer the question on the basis of the following options. You have to select the one that best describes the two statements.

Assertion: Nitrobenzene is used as a solvent in Friedel-Craft's reaction.

Reason: Fusion of nitrobenzene with solid $\mathrm{KOH}$ gives a low yield of a mixture of $o$-and $p$-nitro phenols.

Directions: Each of these questions contain an assertion followed by reason. Read them carefully and answer the question on the basis of the following options. You have to select the one that best describes the two statements.

Assertion: Nitrobenzene cannot undergo Friedel-Craft's reaction.

Reason: Friedel-Craft reaction is an electrophilic substitution reaction.

Directions: Each of these questions contains an Assertion followed by reason. Read them carefully and answer the question on the basis of following options. You have to select the one that best describes the two statements.

Assertion : Cis-But-$2$-ene and trans-but-$2$-ene when reacted with Cold ${\mathrm{KMnO}}_4$, solution gives meso $2,3$-dihydroxy butane and $\left(\mathrm{dl}\right) 2,3$-dihydroxy butane respectively.

Reason: Cold ${\mathrm{KMnO}}_4$ solution adds two $\mathrm{OH}$ groups by syn addition.