Amongst elements of group 15, the property which decreases down the group is`//`are
I. electronegativity
II. stability of -3 oxidation state
III. acidic nature of oxides
Choose the correct option.

Options

A. II and III
B. Only I
C. Only III
D. All of these

Answer

To solve the question regarding the properties that decrease down the group among the elements of group 15, we will analyze each property one by one.

### Step 1: Identify the Elements of Group 15
Group 15 elements, also known as the nitrogen family, include:
- Nitrogen (N)
- Phosphorus (P)
- Arsenic (As)
- Antimony (Sb)
- Bismuth (Bi)

### Step 2: Analyze Electronegativity
Electronegativity is the ability of an atom to attract electrons in a chemical bond.
- **Trend**: Electronegativity decreases down the group due to the increase in atomic radius (more electron shells) which reduces the effective nuclear charge experienced by the valence electrons.
- **Conclusion**: Electronegativity decreases down the group.

### Step 3: Analyze Stability of -3 Oxidation State
The -3 oxidation state is most stable for nitrogen and becomes less stable as we move down the group.
- **Trend**: Nitrogen can easily accommodate three additional electrons, while heavier elements like bismuth can only exhibit positive oxidation states (e.g., +3).
- **Conclusion**: Stability of the -3 oxidation state decreases down the group.

### Step 4: Analyze Acidic Nature of Oxides
The acidic nature of oxides is influenced by the non-metallic character of the element.
- **Trend**: As we move down the group, the non-metallic character decreases and the metallic character increases. Non-metal oxides are generally acidic, while metal oxides are basic.
- **Conclusion**: The acidic nature of oxides decreases down the group.

### Step 5: Final Conclusion
Based on the analysis:
- I. Electronegativity decreases down the group.
- II. Stability of -3 oxidation state decreases down the group.
- III. Acidic nature of oxides decreases down the group.

Thus, all the properties mentioned in the question decrease down the group.

### Correct Option
The correct option is: **All of these (Option 4)**.

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