Question

In Carius tube, an organic compound ‘X’ is treated with sodium peroxide to form a mineral acid ‘Y’. The solution of \(BaCl_2\), is added to ‘Y’ to form a precipitate ‘Z’. ‘Z’ is used for the quantitative estimation of an extra element. ‘X’ could be

• A. A nucleotide
• B. Chioroxylenol
• C. Methionine
• D. Cytosine

Answer 1

The Correct Option is C

To solve this problem, we need to analyze the chemical reactions involved with the organic compound 'X' and understand the step-wise reactions leading to the formation of precipitate 'Z'. Below is a detailed explanation:

1. An organic compound 'X' is treated with sodium peroxide which often results in oxidation. In this reaction sequence, methionine is the correct candidate, as it contains sulfur.
2. Methionine (C_5H_{11}NO_2S) upon oxidation with sodium peroxide results in the formation of sulfuric acid (H_2SO_4), which we refer to as the mineral acid 'Y'.
3. Next, we add a solution of barium chloride (BaCl_2) to 'Y'. This combination typically results in a precipitation reaction where barium sulfate (BaSO_4) is formed as a precipitate 'Z'. This is a classic test for the presence of sulfate ions in solution.
4. The precipitate 'Z', i.e., barium sulfate, is used for quantitative estimation of sulfur, which is an extra element in methionine. Thus, the presence of sulfur in methionine results in the formation of the precipitation product 'Z'.

By following these steps, we can conclude that 'X' could be methionine, since it satisfies the conditions where it gets oxidized to form sulfuric acid which reacts with BaCl_2 to form barium sulfate precipitate.

Justification for Rejection of Other Options:

• A nucleotide and cytosine do not primarily involve sulfur reactions in oxidations that would result in sulfate ion production.
• Chloroxylenol mainly consists of carbon, hydrogen, and chlorine atoms and lacks sulfur for production of sulfuric acid.

Therefore, the correct choice is methionine.