Question

Given below are two statements
Statement I: In wet tri-acids oxidation, $\text{HNO}_3 - \text{H}_2\text{SO}_4 - \text{HClO}_4$ are used for release of nutrients from plants tissues.
Statement II: In tri-acid mixture AR Grade concentration $\text{HNO}_3$, $\text{H}_2\text{SO}_4$ and $\text{HClO}_4$ are used in the ratio of 4 : 1 : 10, respectively.
In light of the above statements, choose the correct answer from the options given below

• A. Both Statement I and Statement II are true
• B. Both Statement I and Statement II are false
• C. Statement I is true but Statement II is false
• D. Statement I is false but Statement II is true

Hint:

In wet tri-acid digestion, nitric acid (\(\text{HNO}_3\)) is always the dominant component (typically in a \( 9:1:4 \) or \( 10:1:4 \) ratio) to safely initiate the oxidation of organic matter before perchloric acid reacts.

Answer 1

The Correct Option is C

Step 1: Understanding the Concept:
Wet digestion or wet oxidation is a sample preparation method used to break down the organic matrix of plant tissues, releasing mineral nutrients into solution for elemental analysis.
This is commonly performed using concentrated oxidizing acids.
Detailed Explanation:
Let us evaluate both statements:
- Statement I: The tri-acid mixture consisting of concentrated nitric acid (\(\text{HNO}_3\)), sulfuric acid (\(\text{H}_2\text{SO}_4\)), and perchloric acid (\(\text{HClO}_4\)) is a standard reagent used for the wet digestion of plant tissue samples. This mixture digests organic matter and releases mineral elements (such as P, K, Ca, Mg, and micronutrients) into solution for analysis. Thus, Statement I is true.
- Statement II: The standard mixing ratio of concentrated \(\text{HNO}_3 : \text{H}_2\text{SO}_4 : \text{HClO}_4\) for wet digestion is typically \( 9 : 1 : 4 \) or \( 10 : 1 : 4 \). Nitric acid is the dominant component because it initiates the oxidation of easily oxidizable organic matter. Perchloric acid is highly explosive when heated with untreated organic matter and is kept at a lower ratio to complete the digestion of resistant fractions. Using a ratio of \( 4 : 1 : 10 \) is incorrect and unsafe. Thus, Statement II is false.

Step 2: Final Answer:
Statement I is true, but Statement II is false, corresponding to Option (C).