Ionic radii of :

Options

A. `Ti^(4+) lt Mn^(7+)`
B. `.^(35)CI^(-) lt .^(37)CI^(-)`
C. `K^(+) gt CI^(-)`
D. `P^(3+) gt P^(5+)`

Explanation

To determine the correct order of ionic radii among the given ions, we need to analyze the charges and the nature of the ions involved. Here is a step-by-step solution:

### Step 1: Understand Ionic Radii
Ionic radii refer to the size of an ion in a crystal lattice. The size of an ion is influenced by its charge; cations (positively charged ions) are generally smaller than their parent atoms because they have lost electrons, leading to a higher effective nuclear charge (Z effective) acting on the remaining electrons. Conversely, anions (negatively charged ions) are larger than their parent atoms because they have gained electrons, which increases electron-electron repulsion.

**Hint:** Remember that cations are smaller than their neutral atoms, and anions are larger than their neutral atoms.

### Step 2: Analyze the Given Ions
1. **Ti^4+ vs. Mn^7+:**
- Ti^4+ has lost 4 electrons, while Mn^7+ has lost 7 electrons.
- Since Mn^7+ has lost more electrons, it will have a smaller ionic radius than Ti^4+.

**Conclusion:** Ti^4+ > Mn^7+ is incorrect.

**Hint:** Compare the number of electrons lost to determine which ion is smaller.

2. **Cl-35 vs. Cl-37:**
- Both ions are isotopes of chlorine and have the same number of protons and electrons.
- The difference in mass does not affect the ionic radius significantly; thus, both ions will have similar ionic radii.

**Conclusion:** Cl-35 = Cl-37 is incorrect.

**Hint:** Isotopes have the same charge and electron configuration, so their ionic radii are similar.

3. **K^+ vs. Cl^-:**
- K^+ is a cation and Cl^- is an anion.
- Anions are larger than cations because they have more electrons, leading to increased electron-electron repulsion.

**Conclusion:** K^+ < Cl^- is incorrect.

**Hint:** Remember that anions are always larger than cations.

4. **P^3+ vs. P^5+:**
- P^3+ has lost 3 electrons, while P^5+ has lost 5 electrons.
- Since P^5+ has lost more electrons, it will have a smaller ionic radius than P^3+.

**Conclusion:** P^3+ > P^5+ is correct.

**Hint:** Compare the number of electrons lost to determine which ion is larger.

### Final Conclusion
The correct order of ionic radii based on the analysis is:
- P^3+ > P^5+

Thus, the correct answer is option D.