The value of four quantum number for the last electron of atom of element 'X' are n=7, l=1,m=+1 and s=+1/2 or -1/2 and vlaue of spin magnetic momentum for element 'X' is zero element 'X' has two isotopes (I) `""_(Z)^(A)X and ` (II) `""_(Z)^(B)X`.
Q. The incorrect statement regarding element 'X' is:

Options

A. Element 'X' belongs to 18th group
B. Number of unpaired electrons in element 'X' is zero
C. Atomic number of element 'X' is 118
D. X' is representative element

Explanation

To solve the question regarding element 'X' and identify the incorrect statement, we will analyze the information given about the quantum numbers and the properties of the element.

### Step-by-Step Solution:

1. **Understanding Quantum Numbers**:
- The four quantum numbers for the last electron of element 'X' are:
- Principal quantum number (n) = 7
- Azimuthal quantum number (l) = 1
- Magnetic quantum number (m) = +1
- Spin quantum number (s) = +1/2 or -1/2
- The values indicate that the last electron is in the 7p orbital (since l=1 corresponds to p orbitals).

2. **Determining the Electron Configuration**:
- Since the spin magnetic moment for element 'X' is zero, this indicates that there are no unpaired electrons.
- For the 7p orbital to have no unpaired electrons, it must be completely filled, which means the electron configuration is 7p^6.

3. **Identifying the Element**:
- An element with the configuration of 7p^6 corresponds to the noble gas Radon (Rn), which has an atomic number of 86.
- However, the question states that element 'X' has an atomic number of 118, which corresponds to the element Oganesson (Og).

4. **Analyzing the Statements**:
- **Statement 1**: "Element X belongs to the 18th group."
- This is true because noble gases are in group 18.
- **Statement 2**: "The number of unpaired electrons in X are 0."
- This is also true since the spin magnetic moment is zero.
- **Statement 3**: "Atomic number of element X is 118."
- This is true as Oganesson has an atomic number of 118.
- **Statement 4**: "X is a representative element."
- This is incorrect because representative elements are those whose outermost shell is not completely filled. Since element 'X' has a filled outer shell (7p^6), it is not a representative element.

5. **Conclusion**:
- The incorrect statement regarding element 'X' is that "X is a representative element."

### Final Answer:
The incorrect statement regarding element 'X' is: "X is a representative element."

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