`Be^(2+)` is isoelectronic with which of the following ions ?

Options

A. `H^(+)`
B. `Li^(+)`
C. `Na^(+)`
D. `Mg^(2+)`

Explanation

To determine which ion is isoelectronic with Be²⁺ (Beryllium ion), we need to follow these steps:

### Step 1: Determine the Electron Configuration of Be²⁺
Beryllium (Be) has an atomic number of 4, which means it has 4 electrons in its neutral state. When it loses 2 electrons to form Be²⁺, it has:
- Total electrons in Be²⁺ = 4 - 2 = 2 electrons.

### Step 2: Identify Isoelectronic Species
Isoelectronic species are atoms or ions that have the same number of electrons. Since Be²⁺ has 2 electrons, we need to find other ions that also have 2 electrons.

### Step 3: Analyze Common Ions
- **He (Helium)**: Helium has 2 electrons.
- **Li⁺ (Lithium ion)**: Lithium has 3 electrons in its neutral state. When it loses 1 electron to form Li⁺, it has 2 electrons.
- **H⁻ (Hydride ion)**: The hydrogen atom has 1 electron. When it gains an electron, it becomes H⁻, which has 2 electrons.

### Step 4: Conclusion
The ions that are isoelectronic with Be²⁺ (which has 2 electrons) are:
- He (Helium)
- Li⁺ (Lithium ion)
- H⁻ (Hydride ion)

However, in the context of common ions, Li⁺ is often highlighted as a relevant isoelectronic species.

### Final Answer
Be²⁺ is isoelectronic with Li⁺ (Lithium ion).

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