Question

Schiff’s reagent gives pink colour with:
A. Acetone
B. Acetaldehyde
C. Ethyl alcohol
D. Methyl acetate

Answer 1

Hint: First we must know the use of Schiff’s reagent. Schiff’s reagent is used in qualitative tests of aldehydes.

Complete step by step answer
The product of reaction of a dye formulation such as sodium bisulfite and fuchsin, pararosaniline (aromatic methyl group is absent) and a new fuchsin is Schiff's reagent. This reagent is prepared by passing sulphur dioxide through fuchsia dye.
An aldehyde reacts with Schiff’s reagent to produce a product of bright red colour. So, the identification of the aldehyde group in a compound can be detected by reacting the compound with Schiff’s reagent.

So, the correct option is B.

Generally, ketones do not respond to the reaction of Schiff’s reagent. If the reaction is subjected to heat, then the reaction gives light pink colour. So, methyl ketones will not give red coloured product on reaction with Schiff’s reagent. So, Option A is not correct.
Alcohol and ester do not react with Schiff’s reagent. So, ethyl alcohol and methyl acetate will not give red colour on reaction with Schiff’s reagent. So, option C and D are not correct.

Additional Information:
Schiff’s reagent distinguishes between primary and secondary alcohols. On reacting an aldehyde with Schiff’s reagent, if its colour changed to red quickly, then, the aldehyde was formed from a primary alcohol. If no colour change occurs Schiff’s reagent, then, the alcohol is secondary.

Note: Aldehydes react with Schiff’s reagent to give red colored products. So, acetaldehyde produces red coloured products. Ketones generally do not react with Schiff’s reagent.