Question

Which of the following tests is not used for testing of proteins?
(A) Millon’s test
(B) Molisch's test
(C) Biuret test
(D) Ninhydrin test

Answer 1

Hint: In these types of questions study each option one by one and then check whether this option holds true for the statement given in question or not. Check the substrate of all the processes or tests given in the option.

Complete Step by Step Solution:
Protein is a polymer of amino acid. There are six tests used for detection of amino acids they are (a) ninhydrin test, (b) biuret test, (c) xanthoproteic test, (d) millon’s test, (e) hopkin’s test, (f) nitroprusside test.
Molisch's test is used in detection of carbohydrates; it is not used in detection of amino acids that are not used in detection of proteins.
So, the tests given in options (A), (C), (D) are used in detection of proteins (as they are used in detection of amino acids) so these options cannot be the correct answer.
Therefore, it is now clear that only option (B), that is molisch's test, is not used for the detection of proteins. (As it is not used for detection of amino acids).
So option (B) is the correct answer.

Note: Note that whenever any reaction takes place, the larger polymeric form breaks into smaller monomeric forms and these small monomeric forms take part in the desired reaction. Similarly in this question as well protein itself will not be a particle in the reaction but smaller monomeric units that are amino acids will take part in the reaction. So, in such questions always break the polymer into its monomeric units and then check whether this monomer will show the particular reaction or not.