The incorrect order of radius is:

Options

A. `Cu^(-) gt Cu gt Cu^(+)`
B. `Sc^(3+) gt K^(+) gt S^(2-)`
C. `Ni lt Cu lt Zn`
D. All of these

Answer

To determine the incorrect order of ionic radii, we need to analyze the trends in ionic sizes based on the charge of ions and their position in the periodic table. Here's a step-by-step solution:

### Step 1: Understand Ionic Radii Trends
- **Cations vs. Anions**: Cations (positively charged ions) are smaller than their parent atoms because they lose electrons, leading to a higher effective nuclear charge (Z_eff) which pulls the remaining electrons closer to the nucleus. Conversely, anions (negatively charged ions) are larger than their parent atoms because they gain electrons, which increases electron-electron repulsion and decreases the effective nuclear charge felt by the outermost electrons.

### Step 2: Compare Ionic Sizes
- **Charge Effect**: The more positive the charge of a cation, the smaller its radius. For example, \( \text{Na}^+ \) is larger than \( \text{Mg}^{2+} \) because \( \text{Mg}^{2+} \) has a higher positive charge, pulling its electrons closer.
- **Anions**: Anions are larger than their parent atoms. For example, \( \text{S}^{2-} \) is larger than \( \text{S} \) because it has gained two electrons.

### Step 3: Analyze Given Options
- Let's assume we have the following ions to compare: \( \text{Cu}^{2+}, \text{Cu}, \text{Sc}^{3+}, \text{K}, \text{S}^{2-}, \text{Zn} \).
- According to the trends:
- \( \text{S}^{2-} \) will be the largest due to being an anion.
- \( \text{K} \) will be larger than cations like \( \text{Cu}^{2+} \) and \( \text{Sc}^{3+} \).
- \( \text{Sc}^{3+} \) will be smaller than \( \text{Cu}^{2+} \) because it has a higher charge.
- \( \text{Zn} \) will have a relatively larger radius compared to transition metals with higher positive charges.

### Step 4: Identify the Incorrect Order
- From the analysis, if the order presented in the options is incorrect, it would likely misplace the sizes of cations and anions based on their charges.

### Conclusion
- The incorrect order of radius is identified as option B, where the expected trend based on ionic charges is not followed.