In multi-electron atom 4s-orbital is lower in energy than

Options

A. 3d-orbital
B. 3p-oribital
C. 2s-orbital
D. 2p-orbital

Answer

To determine which orbitals have higher energy than the 4s orbital in a multi-electron atom, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Energy Levels of Orbitals**:
In multi-electron atoms, the energy levels of orbitals are affected by both the principal quantum number (n) and the azimuthal quantum number (l). The general order of energy levels for orbitals is:
- 1s < 2s < 2p < 3s < 3p < 4s < 3d < 4p < 5s < 4d < 5p < 6s < 5d < 6p < 7s < 6d < 7p

2. **Identify the Position of the 4s Orbital**:
From the above order, we can see that the 4s orbital is situated before the 3d orbital. This indicates that the 4s orbital is lower in energy than the 3d orbital.

3. **Compare 4s with Other Orbitals**:
- **3d Orbital**: As established, 4s < 3d, so 4s is lower in energy than 3d.
- **3p Orbital**: The 3p orbital is lower in energy than the 4s orbital (3p < 4s).
- **2s Orbital**: The 2s orbital is also lower in energy than the 4s orbital (2s < 4s).
- **2p Orbital**: Similarly, the 2p orbital is lower in energy than the 4s orbital (2p < 4s).

4. **Conclusion**:
In a multi-electron atom, the 4s orbital is lower in energy than the 3d orbital. Therefore, the correct answer to the question is that the 4s orbital is lower in energy than the 3d orbital.

### Final Answer:
In a multi-electron atom, the 4s orbital is lower in energy than the 3d orbital.

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