To determine which set of ions represents a collection of isoelectronic species, we need to find ions that have the same number of electrons. Let's analyze each option step by step.
### Step-by-Step Solution:
**Step 1: Understand Isoelectronic Species**
- Isoelectronic species are ions or atoms that have the same number of electrons.
**Step 2: Analyze Each Option**
**Option 1: K⁺, Ca²⁺, Sc³⁺, Cl⁻**
- K (Potassium) has an atomic number of 19. When it loses one electron (K⁺), it has 18 electrons.
- Ca (Calcium) has an atomic number of 20. When it loses two electrons (Ca²⁺), it also has 18 electrons.
- Sc (Scandium) has an atomic number of 21. When it loses three electrons (Sc³⁺), it has 18 electrons.
- Cl (Chlorine) has an atomic number of 17. When it gains one electron (Cl⁻), it has 18 electrons.
**Conclusion for Option 1: All four ions have 18 electrons. Therefore, they are isoelectronic.**
**Step 3: Check Other Options**
**Option 2: Na⁺, Mg²⁺, Al³⁺, Cl⁻**
- Na (Sodium) has an atomic number of 11. When it loses one electron (Na⁺), it has 10 electrons.
- Mg (Magnesium) has an atomic number of 12. When it loses two electrons (Mg²⁺), it has 10 electrons.
- Al (Aluminum) has an atomic number of 13. When it loses three electrons (Al³⁺), it has 10 electrons.
- Cl (Chlorine) has an atomic number of 17. When it gains one electron (Cl⁻), it has 18 electrons.
**Conclusion for Option 2: Na⁺, Mg²⁺, and Al³⁺ have 10 electrons, while Cl⁻ has 18 electrons. They are not isoelectronic.**
**Option 3: K⁺, Cl⁻, Mg²⁺**
- K⁺ has 18 electrons (as calculated before).
- Cl⁻ has 18 electrons (as calculated before).
- Mg²⁺ has 10 electrons (as calculated before).
**Conclusion for Option 3: K⁺ and Cl⁻ have 18 electrons, but Mg²⁺ has 10 electrons. They are not isoelectronic.**
**Option 4: Na⁺, Ca²⁺**
- Na⁺ has 10 electrons (as calculated before).
- Ca²⁺ has 18 electrons (as calculated before).
**Conclusion for Option 4: Na⁺ has 10 electrons, while Ca²⁺ has 18 electrons. They are not isoelectronic.**
### Final Answer:
The only set of ions that represents a collection of isoelectronic species is **Option 1: K⁺, Ca²⁺, Sc³⁺, Cl⁻**.
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