Regarding phenol the correct statement are

A) It reacts with ${\mathrm{Br}}_2/{\mathrm{CS}}_2$  to give a mixture of o-bromophenol and p - bromophenol

B)In Reimer-Tiemann reaction, on treating phenol with chloroform in the presence of sodium 1 hydroxide, a - CHO group is introduced at ortho position of benzene ring.

C) In Kolbe’s reaction it gives salicylic acid

D) On oxidation with   ${\mathrm{K}}_2{\mathrm{Cr}}_2{\mathrm{O}}_7+{\mathrm{H}}_2{\mathrm{SO}}_4$   it gives a conjugated diketone

detailed solution

Correct option is C

• Phenol reacts with bromine in CS₂​ at low temperature to give o and p-bromophenol.

• In Reimer-Tiemann reaction, on treating phenol with chloroform in the presence of sodium 1 hydroxide, a - CHO group is introduced at ortho position of benzene ring.

• Sodium phenoxide is generated by treating phenol with sodium hydroxide. It is treated with carbon dioxide to form ortho-hydroxy benzoic acid(salicylic acid).

• The product formed when phenol is treated with acidified solution of Na₂​Cr₂​O₇​ is benzoquinone a conjugated diketone. It is an oxidation reaction.