A positive ion having just one electron ejects it if a photon of wavelength `228Å` or less is absorbed by it. Identify the ion

Explanation

To solve the problem, we need to identify the positive ion that ejects its only electron when it absorbs a photon of wavelength 228 Å or less. We will follow these steps:

### Step 1: Calculate the Energy of the Photon

The energy of a photon can be calculated using the formula:
\[ E = \frac{12400}{\lambda} \]
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