Assertion: Nuclear density is greater than atomic density.
Reason: Nuclear size (volume) is greater than atomic size.

Options

A. If both assertion and reason are correct and reason is a correct explanation o f the assertion.
B. If both assertion and reason are correct but reason is not the correct explanation o f assertion.
C. If assertion is correct but reason is incorrect.
D. If assertion is incorrect but reason is correct

Answer

To solve the question, we need to analyze the assertion and the reason provided:

**Assertion:** Nuclear density is greater than atomic density.
**Reason:** Nuclear size (volume) is greater than atomic size.

### Step-by-Step Solution:

1. **Understanding Nuclear Density:**
- Nuclear density is defined as the mass of the nucleus divided by its volume.
- Mathematically, it can be expressed as:
\[ \text{Density of nucleus} = \frac{\text{Mass of nucleus}}{\text{Volume of nucleus}} \]

2. **Understanding Atomic Density:**
- Atomic density is defined as the mass of the atom divided by its volume.
- It can be expressed as:
\[ \text{Density of atom} = \frac{\text{Mass of atom}}{\text{Volume of atom}} \]

3. **Comparing Masses:**
- The mass of the nucleus is approximately equal to the mass of the atom because the mass of electrons is negligible compared to the mass of protons and neutrons.
- Therefore, we can say:
\[ \text{Mass of nucleus} \approx \text{Mass of atom} \]

4. **Comparing Volumes:**
- The volume of the nucleus is much smaller than the volume of the atom. This is due to the fact that most of the atom's space is occupied by the electron cloud, which is relatively large compared to the nucleus.
- Thus, we have:
\[ \text{Volume of nucleus} \ll \text{Volume of atom} \]

5. **Calculating Densities:**
- Since the mass of the nucleus is approximately equal to the mass of the atom, but the volume of the nucleus is much smaller, we can conclude that:
\[ \text{Density of nucleus} = \frac{\text{Mass}}{\text{Volume}} \text{ will be much greater than } \text{Density of atom} \]
- Therefore, the assertion that nuclear density is greater than atomic density is **correct**.

6. **Analyzing the Reason:**
- The reason states that nuclear size (volume) is greater than atomic size (volume). This is incorrect because we established that the volume of the nucleus is much smaller than the volume of the atom.
- Hence, the reason is **incorrect**.

### Conclusion:
- The assertion is correct, while the reason is incorrect. Therefore, the correct answer is that the assertion is true, but the reason is false.

### Final Answer:
- **Assertion:** True
- **Reason:** False
- **Conclusion:** Assertion is correct, but the reason is incorrect.

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