21.

The reagent commonly used to determine hardness of water titrimetrically is

• oxalic acid

• disodium salt of EDTA

• sodium citrate

• sodium thiosulphate

On dissolving moderate amount of sodium metal in liquid NH₃ at low temperature, which one of the following does not occur?

• Blue coloured solution is obtained.

• Na⁺ ions are formed in the solution.

• Liquid NH₃ becomes good conductor of electricity

• Liquid ammonia remains diamagnetic

The ligand called $\mathrm{\pi }$ acid is

• CO

• NH₃

• C₂O${}_4^{2-}$

• ethylene diamine

IUPAC name of the following compound is

• 3-methyl cyclohexane

• 1-methyl cyclohex-2-ene

• 6-methyl cyclohexene

• 1-methyl cyclohex-5-ene

The ortho/para directing group among the following is

• COOH

• CN

• COCH₃

• NHCOCH₃

The treatment of benzene with isobutene in the presence of sulphuric acid gives

• iso -butyl benzene

• tert -butyl benzene

• n -butyl benzene

• no reaction

The most reactive nucleophile among the following is

• CH₃O^-

• C₆H₅O^-

• (CH₃)₂CHO^-

• (CH₃)₃CO^-

The absolute configuration of the following compound is

• 2 S, 3 R

• 2 S, 3 S

• 2 R, 3 S

• 2 R, 3 R

Among the following, the achiral amino acid is

• 2-ethylalanine

• 2-methylglycine

• 2-hydroxymethyl serine

• tryptophan

Nitrobenzene gives N-phenylhydroxylamine by

• Sn/HCl

• H₂/Pd-C

• Zn/NaOH

• Zn/NH₄Cl