According to aufbau principle, the correct order of energy of 3d,4s and 4p-orbitals is

Options

A. `4plt3dlt4s`
B. `4slt4plt3d`
C. `4slt3dlt4p`
D. `3dlt4slt4p`

Answer

To determine the correct order of energy for the 3d, 4s, and 4p orbitals according to the Aufbau principle, we will analyze the order in which these orbitals are filled based on their energy levels.

### Step-by-Step Solution:

1. **Understand the Aufbau Principle**: The Aufbau principle states that electrons fill atomic orbitals in order of increasing energy levels. The order of filling is determined by the relative energies of the orbitals.

2. **Identify the Orbitals**: We need to consider the 3d, 4s, and 4p orbitals.

3. **Energy Level Order**: The general order of filling orbitals based on energy levels is:
- 1s
- 2s
- 2p
- 3s
- 3p
- 4s
- 3d
- 4p
- 4d
- 5s
- 4f
- 5p
- 5d
- 6s
- 5f
- 6p
- 6d
- 7s

4. **Determine the Order for 3d, 4s, and 4p**:
- From the order above, we see that the 4s orbital is filled before the 3d orbital.
- The 3d orbital is filled after the 4s orbital but before the 4p orbital.
- Therefore, the order of energy levels is: 4s < 3d < 4p.

5. **Conclusion**: The correct order of energy for the orbitals is:
- 4s < 3d < 4p

### Final Answer:
The correct order of energy of 3d, 4s, and 4p orbitals according to the Aufbau principle is:
**4s < 3d < 4p**