D) Physical Change, I would argue, because you can reverse this change by boiling off (evaporating) the water. But there are arguments for both physical and chemical change being what occurs.
A physical change results in a change of the material's appearance, but no new chemical products result. A chemical change involves a chemical reaction, with new substances produced as a result of the change.
Answer:

Explanation:
Hello,
In this case, we could considering this as a redox titration:

Thus, the balance turns out (by adding both hydrogen ions and water):

Thus, by stoichiometry, the grams of Fe+2 ions result:

Finally, the mass percent is:

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Explanation:
The boy with the help of litmus paper can easily decide it as follows:
(i) The drink that would turn a red litmus to blue would surely be basic in nature.
(ii) The drink that turns a blue litmus to red is be acidic in nature.
(iii) The drink that would not be affected by both red and blue litmus would is neutral in nature.
The test can be done with help of phenolphthalein or the methyl orange these reagents also show different color in different medium.