In which of the following pairs first partner is more soluble in water than second partner ?

Options

A.
B. NaCl and AgCl
C. `Be(OH)_(2)` and `Ba(OH)_(2)`
D.

Answer

To determine which of the first partners in the given pairs is more soluble in water than the second partner, we will analyze each pair based on their solubility characteristics and the presence of hydrogen bonding.

### Step-by-Step Solution:

1. **Analyze the first pair: Ortho-nitrophenol and Para-nitrophenol**
- **Ortho-nitrophenol** has a hydroxyl (-OH) group and a nitro (-NO2) group in the ortho position. This arrangement allows for hydrogen bonding with water.
- **Para-nitrophenol** also has a hydroxyl group and a nitro group, but due to its structure, it can form intramolecular hydrogen bonding. This intramolecular bonding reduces its ability to interact with water.
- **Conclusion**: Ortho-nitrophenol is more soluble in water than para-nitrophenol.

2. **Analyze the second pair: NaCl and AgCl**
- **NaCl** is a highly soluble ionic compound in water due to its ability to dissociate into Na+ and Cl- ions.
- **AgCl** is known to be sparingly soluble in water, forming a white precipitate.
- **Conclusion**: NaCl is more soluble in water than AgCl.

3. **Analyze the third pair: Be(OH)2 and Ba(OH)2**
- **Be(OH)2** is nearly insoluble in water due to its higher lattice energy compared to its hydration energy.
- **Ba(OH)2**, on the other hand, is more soluble in water as it has a lower lattice energy and can dissociate effectively.
- **Conclusion**: Ba(OH)2 is more soluble in water than Be(OH)2.

4. **Analyze the fourth pair: Para-hydroxybenzoic acid and Ortho-hydroxybenzoic acid**
- **Para-hydroxybenzoic acid** can form hydrogen bonds with water effectively.
- **Ortho-hydroxybenzoic acid** can also form hydrogen bonds, but it has intramolecular hydrogen bonding that reduces its interaction with water.
- **Conclusion**: Para-hydroxybenzoic acid is more soluble in water than ortho-hydroxybenzoic acid.

### Final Summary:
- The pairs where the first partner is more soluble in water than the second partner are:
- Ortho-nitrophenol > Para-nitrophenol
- NaCl > AgCl
- Para-hydroxybenzoic acid > Ortho-hydroxybenzoic acid