In which case first has higher solubility than second ?
(I)Phenol, Benzene , (II)Nitrobenzene, Phenol , (III)o-Hydroxybenzaldehyde, p-Hydroxy benzaldehyde , (IV)Ethanol, Dimethylether,

Options

A. only I
B. III,IV
C. I,IV
D. I,IV,III

Explanation

### Step-by-Step Solution

1. **Identify the Compounds in Each Case:**
- (I) Phenol and Benzene
- (II) Nitrobenzene and Phenol
- (III) o-Hydroxybenzaldehyde and p-Hydroxybenzaldehyde
- (IV) Ethanol and Dimethyl Ether

2. **Analyze Case (I): Phenol vs. Benzene**
- Phenol contains an -OH (hydroxyl) group, which can form hydrogen bonds with water.
- Benzene, being a non-polar hydrocarbon, cannot form hydrogen bonds.
- **Conclusion:** Phenol has higher solubility than Benzene.

3. **Analyze Case (II): Nitrobenzene vs. Phenol**
- Nitrobenzene has a nitro group (-NO2) which is electron-withdrawing, making it less polar than phenol.
- Phenol, with its -OH group, can form hydrogen bonds with water.
- **Conclusion:** Phenol is more soluble than Nitrobenzene.

4. **Analyze Case (III): o-Hydroxybenzaldehyde vs. p-Hydroxybenzaldehyde**
- o-Hydroxybenzaldehyde can form intramolecular hydrogen bonds, which reduces its ability to interact with water.
- p-Hydroxybenzaldehyde can form intermolecular hydrogen bonds, enhancing its solubility in water.
- **Conclusion:** p-Hydroxybenzaldehyde is more soluble than o-Hydroxybenzaldehyde.

5. **Analyze Case (IV): Ethanol vs. Dimethyl Ether**
- Ethanol has an -OH group that allows it to form hydrogen bonds with water.
- Dimethyl ether, while it has an ether group, does not have an -OH group and cannot form hydrogen bonds as effectively as ethanol.
- **Conclusion:** Ethanol has higher solubility than Dimethyl Ether.

### Final Answer
The cases where the first compound has higher solubility than the second are:
- (I) Phenol > Benzene
- (IV) Ethanol > Dimethyl Ether