On moving down the group, the basic nature of hydroxide of boron family.

Options

A. Decreases
B. Increases
C. First decreases then increases
D. Remains same

Answer

To analyze how the basic nature of hydroxides of the boron family changes as we move down the group, we can follow these steps:

### Step 1: Identify the Elements in the Boron Family
The boron family consists of the following elements:
- Boron (B)
- Aluminium (Al)
- Gallium (Ga)
- Indium (In)
- Thallium (Tl)

### Step 2: Write the Hydroxides Formed by These Elements
The hydroxides formed by these elements are:
- Boron hydroxide: \( B(OH)_3 \)
- Aluminium hydroxide: \( Al(OH)_3 \)
- Gallium hydroxide: \( Ga(OH)_3 \)
- Indium hydroxide: \( In(OH)_3 \)
- Thallium hydroxide: \( Tl(OH) \)

### Step 3: Understand the Basic Nature of Hydroxides
The basic nature of hydroxides refers to their ability to donate hydroxide ions (OH⁻) in solution. The stronger the base, the more readily it donates hydroxide ions.

### Step 4: Analyze the Trend in Basic Nature Down the Group
As we move down the group from Boron to Thallium, the basic nature of the hydroxides changes:
- Boron hydroxide is acidic.
- Aluminium hydroxide is amphoteric (can act as both an acid and a base).
- Gallium hydroxide is also amphoteric.
- Indium hydroxide and Thallium hydroxide are basic.

### Step 5: Explain the Reason for the Trend
The increase in basic nature can be attributed to the following factors:
- **Ionization Enthalpy**: As we move down the group, the ionization enthalpy decreases. This is due to the increase in atomic size and the number of electron shells. The outermost electrons are further from the nucleus, making them easier to remove.
- **Bond Strength**: The bond between the metal and hydroxide (M-OH) weakens as the ionization energy decreases. This weakening allows the hydroxide to dissociate more easily, resulting in a stronger basic character.

### Step 6: Conclusion
Thus, the basic nature of hydroxides of the boron family **increases** as we move down the group from Boron to Thallium.

### Final Answer
The basic nature of hydroxides of the boron family increases down the group.

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