Which of the following is not a correct statement regarding the energies of orbitals?

Options

A. The lower the value of (n + l) for an orbital, lower is its energy.
B. Electron in the same subshell have equal energy.
C. Energy of s-orbital is lower than the p-orbital and that of p-orbital is lower than the d-orbital.
D. If two orbitals have same value for (n + l), the orbital with higher value of n will have lower energy.

Explanation

To determine which statement regarding the energies of orbitals is incorrect, we will analyze each option step by step.

### Step 1: Analyze the first statement
**Statement:** The lower the value of n + l of an orbital, lower is its energy.

**Explanation:** According to the Aufbau principle, electrons fill orbitals starting from the lowest energy level. The n + l rule states that orbitals with lower n + l values have lower energies. Therefore, this statement is correct.

### Step 2: Analyze the second statement
**Statement:** Electrons in the same subshell have equal energy.

**Explanation:** Electrons within the same subshell (for example, all 2p electrons) indeed have the same energy. This is a well-established fact in quantum mechanics. Therefore, this statement is also correct.

### Step 3: Analyze the third statement
**Statement:** The energy of s orbital is lower than that of p orbital, and the energy of p orbital is lower than that of d orbital.

**Explanation:** The order of energy levels for these orbitals is well-defined: s < p < d < f. Since s orbitals are closer to the nucleus, they have lower energy compared to p and d orbitals. Thus, this statement is correct.

### Step 4: Analyze the fourth statement
**Statement:** If two orbitals have the same value of n + l, the orbital with the higher value of n will have lower energy.

**Explanation:** This statement is incorrect. For example, consider the 3p and 4s orbitals. Both have the same n + l value of 4 (3 + 1 for 3p and 4 + 0 for 4s). However, the 3p orbital has lower energy than the 4s orbital. Therefore, this statement is indeed incorrect.

### Conclusion
The fourth statement is the incorrect one regarding the energies of orbitals.

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