Which of the following statement about quantum number is correct ?

Options

A. If the value of `l = 0`, the electron distribution in spherical
B. The shape of the orbital is given by magnitic quantum number
C. The Zeman's effect is explaited by magnetic quantum number
D. The spin quantum number the orientations of electrion cloul

Answer

To determine which of the statements about quantum numbers is correct, we will analyze each statement one by one.

### Step 1: Analyze the First Statement
**Statement:** If the value of L equals zero, the electron distribution is spherical.

**Explanation:**
- The azimuthal quantum number (L) determines the shape of the orbital.
- When L = 0, it corresponds to the s orbital, which indeed has a spherical shape.
- Therefore, this statement is **correct**.

### Step 2: Analyze the Second Statement
**Statement:** The shape of the orbital is given by the magnetic quantum number.

**Explanation:**
- The magnetic quantum number (m) describes the orientation of the orbital in space, not its shape.
- The shape of the orbital is determined by the azimuthal quantum number (L).
- Therefore, this statement is **incorrect**.

### Step 3: Analyze the Third Statement
**Statement:** The Zeeman effect is explained by the magnetic quantum number.

**Explanation:**
- The Zeeman effect refers to the splitting of spectral lines in the presence of a magnetic field.
- This phenomenon is indeed related to the magnetic quantum number (m), as it describes the different orientations of the orbitals that can split in a magnetic field.
- Therefore, this statement is **correct**.

### Step 4: Analyze the Fourth Statement
**Statement:** The spin quantum number describes the orientation of an electron cloud.

**Explanation:**
- The spin quantum number (s) actually describes the intrinsic spin of the electron, which can be either +1/2 or -1/2, indicating the direction of the electron's spin (clockwise or counterclockwise).
- It does not describe the orientation of the electron cloud.
- Therefore, this statement is **incorrect**.

### Conclusion
From the analysis:
- The **first statement** is correct: If L = 0, the electron distribution is spherical.
- The **second statement** is incorrect.
- The **third statement** is correct: The Zeeman effect is explained by the magnetic quantum number.
- The **fourth statement** is incorrect.

Thus, the correct statements are the **first and third**.