Answer: A color change would appear immediately because
, would be removed slowly from solution, and would therefore be able to react with starch, is the correct answer.
Explanation:
As the given reaction 2 is as follows.
![l_3^-(aq) + 2S_2O_3^2- (aq) \rightarrow 3I^- (aq) + S_4O_6^2-(aq)](https://tex.z-dn.net/?f=%20l_3%5E-%28aq%29%20%2B%202S_2O_3%5E2-%20%28aq%29%20%5Crightarrow%203I%5E-%20%28aq%29%20%2B%20S_4O_6%5E2-%28aq%29)
If this reaction is slow then the removal of
will be slow in nature.
Since, reaction 3 is fast which is as follows.
![l_3^- (aq) + \text{starch}(aq) \rightarrow 3I^---- starch \text{(bluish black)}](https://tex.z-dn.net/?f=l_3%5E-%20%28aq%29%20%2B%20%5Ctext%7Bstarch%7D%28aq%29%20%5Crightarrow%203I%5E----%20starch%20%5Ctext%7B%28bluish%20black%29%7D)
As reaction 3 is fast in nature then more amount of starch will react with
.
Therefore, we can conclude that a color change would appear immediately because
, would be removed slowly from solution, and would therefore be able to react with starch.