Ortho–Nitrophenol is less soluble in water than p– and m– Nitrophenols because :

o–Nitrophenol shows Intramolecular H–bonding

o–Nitrophenol is more volatile in steam than those of m – and p–isomers

o–Nitrophenol shows Intermolecular H–bonding

Melting point of o–Nitrophenol is lower than those of m–and p–isomers.

Alcohols Phenols and Ethers PYQ — JEE Main 2012 · Shift 0 · Q20 with Solution

View written solutionFree

Correct answer: B

Key idea: solubility in water depends on hydrogen bonding with water
Phenols dissolve in water mainly because the $-OH$ group can form hydrogen bonds with water molecules.
Compare the three nitrophenol isomers

In $o$ -nitrophenol, the $-OH$ group and $-NO_2$ group are adjacent.
This allows intramolecular hydrogen bonding between the hydrogen of $-OH$ and an oxygen of the $-NO_2$ group.

This can be represented as:

\text{$o$-Nitrophenol} \;\to\; \text{intramolecular H-bonding}

Effect of intramolecular H-bonding on solubility
Because the $-OH$ group is already engaged in internal hydrogen bonding, it is less available to form hydrogen bonds with water. Therefore, $o$ -nitrophenol interacts less strongly with water and is less soluble.
Why $m$ - and $p$ -nitrophenol are more soluble
In the meta and para isomers, such intramolecular hydrogen bonding is not possible due to the positions of the groups. So they can form intermolecular hydrogen bonds with water more effectively, increasing solubility.
Check the options

A: $o$ -Nitrophenol is more volatile in steam — true property, but this is a consequence of intramolecular H-bonding, not the direct reason asked for solubility.
B: $o$ -Nitrophenol shows intramolecular H-bonding — correct.
C: $o$ -Nitrophenol shows intermolecular H-bonding — false in this context.
D: Lower melting point is not the reason for lower solubility.

Final answer
Thus, $o$ -nitrophenol is less soluble in water because it shows intramolecular hydrogen bonding.

\boxed{\text{B}}

Comparison with stored correct answer
Stored correct answer = B. My derived answer also = B. Hence, they agree.

View written solutionFree

Correct answer: B

Key idea: solubility in water depends on hydrogen bonding with water
Phenols dissolve in water mainly because the $-OH$ group can form hydrogen bonds with water molecules.
Compare the three nitrophenol isomers

In $o$ -nitrophenol, the $-OH$ group and $-NO_2$ group are adjacent.
This allows intramolecular hydrogen bonding between the hydrogen of $-OH$ and an oxygen of the $-NO_2$ group.

This can be represented as:

\text{$o$-Nitrophenol} \;\to\; \text{intramolecular H-bonding}

Effect of intramolecular H-bonding on solubility
Because the $-OH$ group is already engaged in internal hydrogen bonding, it is less available to form hydrogen bonds with water. Therefore, $o$ -nitrophenol interacts less strongly with water and is less soluble.
Why $m$ - and $p$ -nitrophenol are more soluble
In the meta and para isomers, such intramolecular hydrogen bonding is not possible due to the positions of the groups. So they can form intermolecular hydrogen bonds with water more effectively, increasing solubility.
Check the options

A: $o$ -Nitrophenol is more volatile in steam — true property, but this is a consequence of intramolecular H-bonding, not the direct reason asked for solubility.
B: $o$ -Nitrophenol shows intramolecular H-bonding — correct.
C: $o$ -Nitrophenol shows intermolecular H-bonding — false in this context.
D: Lower melting point is not the reason for lower solubility.

Final answer
Thus, $o$ -nitrophenol is less soluble in water because it shows intramolecular hydrogen bonding.

\boxed{\text{B}}

Comparison with stored correct answer
Stored correct answer = B. My derived answer also = B. Hence, they agree.