How can 2,4,6-trinitrophenol (picric acid) an | vedclass

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(C) Picric acid ($2,4,6$-trinitrophenol) is a strong acid due to the presence of three electron-withdrawing $-NO_2$ groups,which makes it acidic enoug

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Aqueous $FeCl_3$

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(C) Picric acid ($2,4,6$-trinitrophenol) is a strong acid due to the presence of three electron-withdrawing $-NO_2$ groups,which makes it acidic enough to react with $NaHCO_3$ to evolve $CO_2$ gas. However,benzoic acid is a weaker acid compared to picric acid but still reacts with $NaHCO_3$. Actually,the most effective way to distinguish them is using aqueous $FeCl_3$. Phenols,including picric acid,give a characteristic color (often violet,green,or red) with neutral $FeCl_3$ solution due to the formation of a complex,whereas benzoic acid does not give this test. Therefore,aqueous $FeCl_3$ is the correct reagent.

List-$I$	List-$II$
$a$. $(i)$ $NaOH$,$(ii)$ $CO_2$,$(iii)$ $H^{+}$	$i$. Benzoquinone
$b$. $(i)$ Aqueous $NaOH + CHCl_3$,$(ii)$ $H^{+}$	$ii$. Benzene
$c$. $Zn$ dust,$\Delta$	$iii$. Salicylaldehyde
$d$. $Na_2Cr_2O_7, H_2SO_4$	$iv$. Salicylic acid

How can $2,4,6$-trinitrophenol (picric acid) and benzoic acid be distinguished?

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