Assertion (A) : The atomic radii of the electrons of oxygen family are smaller than the atomic radii of corresponding electrons of the nitrogen family
Reason (R ) : The members of oxygen family are all more electronegative and thus have lower value of nuclear than those of the nitrogen family

Options

A. If both (A) and (R ) correct and (R ) is the correct explanation for (A)
B. If both (A) and (R ) correct and (R ) is the correct explanation for (A)
C. If (A) is correct but (R ) is incorrect
D. If (A) is incorrect but (R ) is correct

Explanation

To analyze the assertion and reason provided in the question, we need to break it down step by step.

### Step 1: Understanding the Assertion
The assertion states that "The atomic radii of the electrons of the oxygen family are smaller than the atomic radii of the corresponding electrons of the nitrogen family."

- **Explanation**: The atomic radius generally decreases as we move from left to right across a period in the periodic table. This is due to the increase in nuclear charge (the number of protons in the nucleus) which pulls the electrons closer to the nucleus, resulting in a smaller atomic radius.

### Step 2: Analyzing the Elements
- The nitrogen family includes elements like nitrogen (N), phosphorus (P), arsenic (As), etc.
- The oxygen family includes elements like oxygen (O), sulfur (S), selenium (Se), etc.
- Oxygen is to the right of nitrogen in the periodic table, which supports the assertion that the atomic radius of oxygen (and its family) is smaller than that of nitrogen (and its family).

### Step 3: Understanding the Reason
The reason states that "The members of the oxygen family are all more electronegative and thus have a lower value of nuclear charge than those of the nitrogen family."

- **Explanation**: While it is true that members of the oxygen family are generally more electronegative than those of the nitrogen family, the statement about having a "lower value of nuclear charge" is incorrect. The nuclear charge increases as we move from nitrogen to oxygen because the atomic number increases.

### Step 4: Conclusion
- The assertion is correct: the atomic radii of the oxygen family are indeed smaller than those of the nitrogen family.
- The reason is incorrect: the members of the oxygen family do not have a lower nuclear charge; they actually have a higher nuclear charge due to a greater number of protons.

### Final Answer
- The correct option is that the assertion is correct, but the reason is incorrect.

---