JEE MAIN - Chemistry (2020 - 9th January Evening Slot - No. 4)
A, B and C are three biomolecules. The results
of the tests performed on them are given
below:
$$ \begin{array}{|l|l|l|l|} \hline & \begin{array}{l} \text { Molisch's } \\ \text { Test } \end{array} & \begin{array}{l} \text { Barfoed } \\ \text { Test } \end{array} & \begin{array}{l} \text { Biuret } \\ \text { Test } \end{array} \\ \hline \text { A } & \text { Positive } & \text { Negative } & \text { Negative } \\ \hline \text { B } & \text { Positive } & \text { Positive } & \text { Negative } \\ \hline \text { C } & \text { Negative } & \text { Negative } & \text { Positive } \\ \hline \end{array} $$
A, B and C are respectively :
$$ \begin{array}{|l|l|l|l|} \hline & \begin{array}{l} \text { Molisch's } \\ \text { Test } \end{array} & \begin{array}{l} \text { Barfoed } \\ \text { Test } \end{array} & \begin{array}{l} \text { Biuret } \\ \text { Test } \end{array} \\ \hline \text { A } & \text { Positive } & \text { Negative } & \text { Negative } \\ \hline \text { B } & \text { Positive } & \text { Positive } & \text { Negative } \\ \hline \text { C } & \text { Negative } & \text { Negative } & \text { Positive } \\ \hline \end{array} $$
A, B and C are respectively :
A = Lactose, B = Glucose, C = Albumin
A = Lactose, B = Fructose, C = Alanine
A = Lactose, B = Glucose, C = Alanine
A = Glucose, B = Fructose, C = Albumin
Explanation
The given table provides the results of three tests: Molisch's test, Barfoed's test, and Biuret test for three different biomolecules A, B, and C.
Molisch's Test: Detects carbohydrates. Positive results for A and B indicate that they are carbohydrates.
Barfoed's Test: Specifically for detecting monosaccharides. A positive result for B indicates that B is a monosaccharide, while A's negative result indicates it's not a monosaccharide, implying it might be a disaccharide.
Biuret Test: Used to detect the presence of proteins. Positive result for C indicates that it is a protein.
Given the options, we can analyze them as follows:
- Option A: Lactose (disaccharide), Glucose (monosaccharide), Albumin (protein) - fits the given results.
- Option B: Lactose (disaccharide), Fructose (monosaccharide), Alanine (amino acid) - not a match, as Alanine won't give a positive Biuret test.
- Option C: Lactose (disaccharide), Glucose (monosaccharide), Alanine (amino acid) - same issue as Option B.
- Option D: Glucose (monosaccharide), Fructose (monosaccharide), Albumin (protein) - not a match, as A must be a disaccharide.
Therefore, the correct option is: Option A: A = Lactose, B = Glucose, C = Albumin.
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