Three molecular ionic states, P-R are possible for the amino acid histidine. Identify the correct choice of pH values, respectively for the observation of the ionic states P-R.

The decreasing order of nucleophilicity for the following anions is CH₃C$${\text{O}}_2^ - $$, CH₃O^-, C₆H₅O^-, N$${\text{O}}_3^ - $$

A. CH₃C$${\text{O}}_2^ - $$ > CH₃O^- > C₆H₅O^- > N$${\text{O}}_3^ - $$

B. CH₃O^- > N$${\text{O}}_3^ - $$ > C₆H₅O^- > CH₃C$${\text{O}}_2^ - $$

C. CH₃O^- > C₆H₅O^- > CH₃C$${\text{O}}_2^ - $$ > N$${\text{O}}_3^ - $$

D. C₆H₅O^- > CH₃O^- > N$${\text{O}}_3^ - $$ > CH₃C$${\text{O}}_2^ - $$

The most appropriate sequence of the reactions for carrying out the following conversion

is

A. (i) peracid, (ii) H⁺, (iii) Zn/dil.HCl

B. (i) Alkaline KMnO₄, (ii) NalO₄, (iii) N₂H₄/KOH

C. (i) Alkaline KMnO₄, (ii) H⁺, (iii) Zn/dil.HCl

D. (i) O₃/Me₂S, (ii) NaOEt, (iii) N₂H₄/KOH

Which of the following compounds is expected to show a sharp singlet for one of its protons at δ ≥ 8 ppm in ¹H NMR spectrum, given that this signal remains unaffected on shaking the solution thoroughly with D₂O?

A. CH₃CO₂H

B. CH₃CONHC₆H₅

C. n-C₆H₁₃C ≡ CH

D. n-C₆H₁₃CHO

Conversion of Ph-NH₂ into Ph-CN can be accomplished by

A. reaction with sodium cyanide in the presence of nickel catalyst

B. reaction with chloroform and sodium hydroxide

C. diazotisation followed by reaction with CuCN

D. reaction with ethyl formate followed by thermolysis