Interpret the given tests

We are told that compound $X$:

• is acidic,
• is soluble in $NaOH$,
• is insoluble in $NaHCO_3$,
• gives violet colour with neutral $FeCl_3$.

Use acidity behavior

• Compounds soluble in $NaOH$ are generally acidic enough to form their sodium salts.
• If a compound is insoluble in $NaHCO_3$, then it is not acidic enough to react with sodium bicarbonate.

This helps distinguish:

• Carboxylic acids: react with both $NaOH$ and $NaHCO_3$.
• Phenols: react with $NaOH$ but do not react with $NaHCO_3$ because they are weaker acids than carbonic acid.

So, $X$ is most likely a phenol.

Use the $FeCl_3$ test

Neutral $FeCl_3$ gives a violet/purple colour with phenolic compounds due to formation of a coloured ferric-phenolate complex.

This confirms that $X$ is a phenol.

Conclusion

Therefore, the correct option must be the one corresponding to phenol.

Compare with stored answer

The stored correct answer is B. Since the phenol option is intended here, this matches.