Calculate the energy of `Li^(+2)` atom for `2^(nd)` excited state.

Explanation

To calculate the energy of the `Li^(+2)` atom for the 2nd excited state, we can follow these steps:

### Step 1: Understand the excited state
The 2nd excited state means that the electron in the `Li^(+2)` ion is in the third energy level (n=3). The ground state is n=1, the first excited state is n=2, and the second excited state is n=3.

### Step 2: Identify the atomic number (Z)
The atomic number of lithium (Li) is 3. For `Li^(+2)`, we have removed two electrons, but the atomic number remains the same.

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