Heavy nuclei are having ............... protons than neutrons.

Answer

To solve the question "Heavy nuclei are having ............... protons than neutrons," we need to analyze the relationship between protons and neutrons in heavy nuclei.

### Step-by-Step Solution:

1. **Understanding Heavy Nuclei**:
- Heavy nuclei are defined as those with a large number of nucleons (protons and neutrons). Examples include elements like Uranium and Thorium.

2. **Identifying Protons and Neutrons**:
- The number of protons in a nucleus is given by the atomic number (Z).
- The number of neutrons (N) can be calculated using the formula:
\[ N = A - Z \]
where A is the atomic mass (total number of protons and neutrons).

3. **Example Calculation**:
- Let's take Uranium as an example:
- Atomic number (Z) of Uranium = 92 (this is the number of protons).
- Atomic mass (A) of Uranium = 238.
- Therefore, the number of neutrons (N) is:
\[ N = 238 - 92 = 146 \]

4. **Comparison**:
- From the calculation, we see that for Uranium:
- Number of protons = 92
- Number of neutrons = 146
- This shows that in heavy nuclei, the number of neutrons is greater than the number of protons.

5. **Conclusion**:
- Therefore, we can fill in the blank in the question: "Heavy nuclei are having **fewer** protons than neutrons."

### Final Answer:
Heavy nuclei are having **fewer** protons than neutrons.