Which of the following conclusions regarding the structure of atom is based on Rutherford's `alpha`-particle scattering experiment?

Options

A. The positive charge is concentrated in a very small volume of the atom.
B. The positive charge is scattered with the electrons throughout the atom.
C. The volume occupied by the nucleus is half of the volume of atom.
D. Most of the space in the atom is occupied by the neutrons.

Explanation

To answer the question regarding the conclusions drawn from Rutherford's alpha-particle scattering experiment, we can follow these steps:

### Step 1: Understand the Experiment
Rutherford conducted an experiment where he directed alpha particles at a thin gold foil. Most of the alpha particles passed through the foil with little to no deflection, while some were deflected at large angles.

### Step 2: Draw Conclusions from Observations
From the observations of the experiment, Rutherford drew several key conclusions:
- **Most of the atom is empty space**: Since most alpha particles passed through without deflection, it indicates that the majority of the atom is not filled with matter.
- **Presence of a small, dense nucleus**: The deflections of some alpha particles suggested that there is a small, dense region within the atom that contains positive charge, which he termed the nucleus. This nucleus is where the majority of the atom's mass is concentrated.
- **Positive charge is not spread out**: The deflections indicated that the positive charge is concentrated in the nucleus rather than being spread throughout the atom, as previously suggested by Thomson's model.

### Step 3: Evaluate the Given Options
Now, we can evaluate the options provided in the question:
- **Option A**: The positive charge is concentrated in a very small volume (the nucleus). This is a conclusion from Rutherford's experiment.
- **Option B**: The positive charge is scattered with the electrons throughout the atom. This contradicts Rutherford's findings.
- **Option C**: The volume occupied by the nucleus is half the volume of the atom. This is incorrect; the nucleus occupies a very small fraction of the total atomic volume.
- **Option D**: Most of the space in the atom is occupied by neutrons. This is incorrect as well; most of the space is empty.

### Step 4: Identify the Correct Conclusion
Based on the conclusions drawn from the experiment, the correct answer is **Option A**: The positive charge is concentrated in a very small volume (the nucleus).

### Final Answer
The conclusion regarding the structure of the atom based on Rutherford's alpha-particle scattering experiment is that the positive charge is concentrated in a very small volume known as the nucleus.

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