The spectrum of `He^(+)` is expected to be similar to that of

Options

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

Answer

To determine which element's spectrum is similar to that of \( \text{He}^+ \), we can follow these steps:

### Step 1: Understand the Electronic Configuration
The first step is to identify the electronic configuration of \( \text{He}^+ \). Helium (He) has an atomic number of 2, which means it has 2 electrons in its neutral state. When it loses one electron to become \( \text{He}^+ \), it has only 1 electron left.

- **Electronic Configuration of \( \text{He}^+ \)**: \( 1s^1 \)

### Step 2: Identify Similar Systems
Next, we need to find another ion or atom that has the same electronic configuration of \( 1s^1 \). We can look for ions of other elements that have lost electrons to achieve this configuration.

- **Lithium Ion \( \text{Li}^{2+} \)**: Lithium (Li) has an atomic number of 3 and has 3 electrons. When it loses 2 electrons, it becomes \( \text{Li}^{2+} \) and has 1 electron left.

- **Electronic Configuration of \( \text{Li}^{2+} \)**: \( 1s^1 \)

### Step 3: Conclusion
Since both \( \text{He}^+ \) and \( \text{Li}^{2+} \) have the same electronic configuration of \( 1s^1 \), their spectra will be similar. This is because the spectral lines are determined by the transitions of the electrons between energy levels, and since both systems have only one electron, they will exhibit similar spectral characteristics.

### Final Answer
The spectrum of \( \text{He}^+ \) is expected to be similar to that of \( \text{Li}^{2+} \).

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