Question

In the limit test for Arsenic, which imparts brown colour to mercuric chloride paper?

• A. Arsenic acid
• B. Arsenic oxide
• C. Arsine
• D. Arsenious acid

Hint:

Brown color = Arsine gas ($AsH_{3}$) + Mercuric Chloride paper.

Answer 1

The Correct Option is C

Step 1: Concept
The limit test for Arsenic is based on the Gutzeit test, where arsenic is converted into arsine gas.

Step 2: Meaning
Arsine ($AsH_{3}$) is a gaseous compound produced when arsenic reacts with nascent hydrogen in acidic conditions.

Step 3: Analysis
When arsine gas comes into contact with mercuric chloride ($HgCl_{2}$) paper, it undergoes a chemical reaction that produces a yellow to brown stain. The intensity of this brown color is proportional to the amount of arsenic present in the sample.

Step 4: Conclusion
Therefore, arsine is the specific chemical species responsible for imparting the brown color to the test paper.

Final Answer: (C)