When alpha particles are sent through a thin metal foil most of them go straight through the foil because

Options

A. Alpha particles are much heavier than electrons
B. Alpha particles are positively charged
C. Most part of the atom is empty
D. Alpha particles move with high velocity

Answer

To answer the question "When alpha particles are sent through a thin metal foil most of them go straight through the foil because," we need to analyze the options provided and relate them to the principles of atomic structure, particularly based on Rutherford's gold foil experiment.

### Step-by-Step Solution:

1. **Understanding Alpha Particles**:
Alpha particles are positively charged particles that consist of two protons and two neutrons. They are relatively heavy compared to electrons.

2. **Rutherford's Experiment**:
In Rutherford's gold foil experiment, alpha particles were directed at a thin foil of gold. The observations made during this experiment are crucial to understanding atomic structure.

3. **Observations from the Experiment**:
- Most of the alpha particles passed straight through the foil without any deflection.
- A small fraction of alpha particles were deflected at large angles, and a very few were reflected back.

4. **Conclusion Drawn**:
The fact that most alpha particles passed through the foil indicates that there is a lot of empty space within the atom. The nucleus, which is positively charged, occupies only a small volume of the atom.

5. **Evaluating the Options**:
- **Option 1**: "Alpha particles are much heavier than electrons" - This is true, but it does not explain why they pass through the foil.
- **Option 2**: "Alpha particles are positively charged" - This is also true, but it does not explain the majority passing through.
- **Option 3**: "Most part of the atom is empty" - This is the correct explanation based on Rutherford's findings.
- **Option 4**: "Alpha particles move with high velocity" - While they do move quickly, this does not directly relate to why they can pass through the foil.

6. **Final Answer**:
The correct answer is **Option 3: Most part of the atom is empty**.