The discovery of neutrons became very late because

Options

A. Neutrons are present in the nucleus
B. neutrons are fundamental particles
C. neutrons have no change
D. All of the above

Answer

To answer the question "The discovery of neutrons became very late because," we can analyze the options provided and the reasoning behind the delay in their discovery.

### Step-by-Step Solution:

1. **Understanding Neutrons**: Neutrons are subatomic particles found in the nucleus of an atom alongside protons. Unlike protons, neutrons do not carry any electric charge.

2. **Analyzing the Options**:
- **Option A**: "Neutrons are present in the nucleus" - While this is true, it does not explain why their discovery was delayed.
- **Option B**: "Neutrons are fundamental particles" - This statement is also true, but it does not provide a reason for the delay in discovery.
- **Option C**: "Neutrons have no charge" - This is a significant point. Because neutrons are neutral, they do not respond to electric or magnetic fields, making them difficult to detect using the methods available at the time of their discovery.
- **Option D**: "All of the above" - This option suggests that all previous statements contribute to the reason for the delay.

3. **Conclusion**: The most relevant reason for the late discovery of neutrons is that they have no charge (Option C). This characteristic made them undetectable with the existing experimental techniques that relied on charged particles. Therefore, while all options have some truth, the primary reason is that neutrons have no charge.

### Final Answer:
The discovery of neutrons became very late because neutrons have no charge, which made them difficult to detect. Thus, the correct answer is **Option C**.

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