Question

The solution of Fehling B contains:
(A) acidified Rochelle salt
(B) alkaline sodium potassium citrate
(C) alkaline sodium potassium tartrate
(D) acidified sodium potassium citrate

Answer 1

Fehling solution are generally the alkaline solutions and exists as two solutions i.e. Fehling solution A (copper sulphate) and Fehling solution B (tartrate) and is mostly used to distinguish the aldehyde group(-CHO) and the ketone group( -C=O).

Complete step by step solution:
-Fehling solution is a chemical reagent which is commonly used in the laboratories and is generally the alkaline solution of copper sulphate (II) and a tartrate.
-It is used in the labs to identify the compounds which contain the -CHO group because this -Fehling solution test is given by only the aldehydes and its respective compounds. The -Fehling solution is present in the form of two separate solutions i.e. the Fehling solution A and the Fehling solution B.
-The Fehling A solution consists of the copper sulphate solution (II) and this Fehling solution A is blue in colour due to the presence of copper sulphate solution. on the other hand, the -Fehling B consists of the alkaline solution of the potassium sodium tartrate also known as the Rochelle salt) and this Fehling solution B is colourless in nature.

Hence, the option (C) is correct.

Note: Fehling solution is used in the laboratory to distinguish between the reducing sugars (which contain the aldehyde group) and the non-reducing sugars (which doesn’t contain the aldehyde group) and it is an easy method to detect their presence in the compound.