An electron has a spin quantum number +1/2 and mag netic quantum number-1. It cannot be present in: 

Options

A. d-orbital
B. f-orbital
C. p-orbital
D. s-orbital

Answer

To solve the question, we need to analyze the quantum numbers given for the electron and determine in which orbital it cannot be present. The quantum numbers provided are:

- Spin quantum number (s) = +1/2
- Magnetic quantum number (ml) = -1

### Step 1: Understand the Quantum Numbers
The quantum numbers for an electron include:
1. Principal quantum number (n): Indicates the energy level.
2. Azimuthal quantum number (l): Indicates the subshell (s, p, d, f).
3. Magnetic quantum number (ml): Indicates the orientation of the orbital.
4. Spin quantum number (s): Indicates the spin direction of the electron.

### Step 2: Determine the Possible Values of ml for Each Orbital
- For **s orbital**:
- l = 0
- Possible values of ml = {0}

- For **p orbital**:
- l = 1
- Possible values of ml = {-1, 0, +1}

- For **d orbital**:
- l = 2
- Possible values of ml = {-2, -1, 0, +1, +2}

- For **f orbital**:
- l = 3
- Possible values of ml = {-3, -2, -1, 0, +1, +2, +3}

### Step 3: Analyze the Given Magnetic Quantum Number (ml = -1)
We need to check if ml = -1 can exist in each of the orbitals:
- **s orbital**: ml cannot be -1 (only ml = 0 is allowed).
- **p orbital**: ml = -1 is allowed.
- **d orbital**: ml = -1 is allowed.
- **f orbital**: ml = -1 is allowed.

### Step 4: Conclusion
Since the magnetic quantum number ml = -1 cannot be present in the s orbital (as it only allows ml = 0), the electron cannot be present in the s orbital.

Thus, the correct answer is that the electron cannot be present in the **s orbital**.

### Final Answer
The electron cannot be present in the **s orbital**.

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