Assertion : Binding energy increase with increases atomic mass number.
Reason : Density of nucleus increase with increases in atomic mass number .

Answer

To solve the given question, we will analyze both the assertion and the reason provided.

### Step-by-Step Solution:

1. **Understanding the Assertion**:
- The assertion states that "Binding energy increases with increases in atomic mass number."
- Binding energy (BE) is the energy required to disassemble a nucleus into its constituent protons and neutrons. It is influenced by the mass defect of the nucleus.
- The formula for binding energy can be expressed as:
\[ BE = \Delta m \cdot c^2 \]
where \(\Delta m\) is the mass defect and \(c\) is the speed of light.
- It is important to note that while binding energy does generally increase with atomic mass number for many nuclei, it does not increase uniformly. There are exceptions, particularly for very light or very heavy nuclei.

2. **Evaluating the Reason**:
- The reason states that "Density of nucleus increases with increases in atomic mass number."
- The density of a nucleus can be calculated using the formula:
\[ \text{Density} = \frac{\text{Mass}}{\text{Volume}} = \frac{A \cdot m_u}{\frac{4}{3} \pi r^3} \]
where \(A\) is the atomic mass number and \(r\) is the radius of the nucleus.
- The radius of the nucleus can be approximated using the formula:
\[ r = r_0 A^{1/3} \]
where \(r_0\) is a constant.
- Substituting this into the volume formula gives:
\[ \text{Volume} = \frac{4}{3} \pi (r_0 A^{1/3})^3 = \frac{4}{3} \pi r_0^3 A \]
- Therefore, density can be expressed as:
\[ \text{Density} = \frac{A \cdot m_u}{\frac{4}{3} \pi r_0^3 A} = \frac{3 m_u}{4 \pi r_0^3} \]
- This shows that the density of the nucleus is approximately constant and does not significantly change with the atomic mass number \(A\).

3. **Conclusion**:
- Since the assertion is not universally true and the reason is also incorrect, we conclude that both the assertion and the reason are incorrect.

### Final Answer:
- **Assertion**: Incorrect
- **Reason**: Incorrect