
- AThe first reaction is a redox reaction.
- BWhite precipitate is .
- CAddition of filtrate to starch solution gives blue colour.
- DWhite precipitate is soluble in NaOH solution.
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Correct answer: A, C, D
We analyze the standard aqueous reactions involving zinc salt solution, potassium ferro/ferricyanide, and iodine/starch test implied by the options.
The relevant reaction pattern is:
- A zinc salt such as reacts with potassium ferricyanide to give a white precipitate.
- On further treatment, the filtrate gives a blue colour with starch, indicating liberation/presence of iodine.
- The white precipitate being a zinc compound is amphoteric and dissolves in .
Let us test each statement carefully.
1. Identify the white precipitate
If reacts with ferricyanide ion , the neutral precipitate formed is:
So the white precipitate is:
At first sight this seems to support option B. However, we must check consistency with the other given clues, especially the starch test.
2. Why does starch give blue colour with the filtrate?
A blue colour with starch means iodine is present:
Thus the filtrate must contain or something that generates .
This happens when ferricyanide oxidizes iodide:
Here:
- ferricyanide is reduced to ferrocyanide,
- iodide is oxidized to iodine.
Hence the first reaction must involve a redox process. Therefore statement A is true.
Also, since iodine is formed in solution, the filtrate gives blue colour with starch. Therefore statement C is true.
3. Nature of the precipitate and solubility in NaOH
The white precipitate formed in such zinc-based qualitative reactions behaves amphoterically because zinc compounds dissolve in excess alkali by forming zincate-type species.
Thus the precipitate dissolves in solution. Therefore statement D is true.
4. Check statement B carefully
If the first reaction is redox and ferricyanide is converted to ferrocyanide, then the zinc precipitate obtained after reduction is not necessarily the ferricyanide salt written in option B.
Option B specifically states that the white precipitate is:
But this corresponds to precipitation with ferricyanide ion directly. In the redox setting indicated by options A and C, ferricyanide is reduced to ferrocyanide, so this formula is not the correct identification for the precipitate in the overall reaction context.
Hence B is false.
5. Final evaluation of options
- A: True
- B: False
- C: True
- D: True
Therefore, the correct statements are:
6. Comparison with stored correct answer
Stored correct answer: A, C, D
Our derived answer matches exactly.
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