Given that `Z_(eff)` value of an element `N (Z = 7)` is Y. Then which of the following statements is correct? 

Options

A. `sigma` value for N will be `7+ Y`.
B. `sigma` value for oxygen will be `7.35-Y`
C. `sigma` value for oxygen will be 7-Y.
D. Given information is not sufficient.

Answer

To solve the question regarding the effective nuclear charge (Z_eff) of nitrogen (N, Z = 7), we need to understand the concept of Z_eff and how it is calculated.

### Step-by-Step Solution:

1. **Understanding Z_eff**:
The effective nuclear charge (Z_eff) is calculated using the formula:
\[ Z_{\text{eff}} = Z - \sigma \]
where \( Z \) is the atomic number and \( \sigma \) is the shielding or screening constant.

2. **Identify Given Values**:
For nitrogen (N), the atomic number \( Z = 7 \). We are given that \( Z_{\text{eff}} = Y \).

3. **Set Up the Equation**:
From the formula, we can express the screening constant \( \sigma \):
\[ Y = 7 - \sigma \]
Rearranging gives:
\[ \sigma = 7 - Y \]

4. **Analyze the Statements**:
We need to evaluate the correctness of the statements provided in the options.

5. **Consider the Case for Oxygen (Z = 8)**:
For oxygen, the atomic number is \( Z = 8 \). The effective nuclear charge can similarly be expressed as:
\[ Z_{\text{eff}} = 8 - \sigma' \]
where \( \sigma' \) is the new screening constant for oxygen.

6. **Determine the Screening Constant for Oxygen**:
If we consider that the addition of an electron to the p-shell increases the nuclear charge, we can estimate:
\[ Z_{\text{eff}} = 8 - \sigma' = 8 - (0.35 + \sigma) \]
This implies:
\[ \sigma' = 8 - Y + 0.35 \]

7. **Conclusion**:
Based on the calculations, we can conclude that the effective nuclear charge for nitrogen is influenced by the screening constant, and the correct statement among the options provided relates to the effective nuclear charge of oxygen being higher due to the additional electron in the p-shell.

### Final Answer:
The correct statement is that the effective nuclear charge for oxygen is higher than that for nitrogen due to the additional electron in the p-shell.