Arrange the following orbitals in the order in which they are filled with electrons and justify the order: 6s, 5d, 6p, 75, Sf.

Explanation

To arrange the orbitals 6s, 5d, 6p, 7s, and 5f in the order in which they are filled with electrons, we will use the n + l rule. This rule states that orbitals are filled in order of increasing values of n + l, where n is the principal quantum number and l is the azimuthal quantum number. If two orbitals have the same n + l value, the one with the lower n value is filled first.

### Step-by-Step Solution:

1. **Identify n and l for each orbital:**
- For **6s**: n = 6, l = 0 → n + l = 6 + 0 = 6
- For **5d**: n = 5, l = 2 → n + l = 5 + 2 = 7
- For **6p**: n = 6, l = 1 → n + l = 6 + 1 = 7
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