Explanation:

Introduction:
The alpha scattering experiment, also known as the Geiger-Marsden experiment, was conducted by Hans Geiger and Ernest Marsden in 1909. This experiment was crucial in understanding the structure of the atom and led to the development of the nuclear model of the atom.

Objective of the experiment:
The objective of the alpha scattering experiment was to determine the structure of the atom, specifically the distribution of positive charge within the atom.

Experimental setup:
In the experiment, a thin sheet of gold foil was bombarded with alpha particles (helium nuclei). The alpha particles were emitted from a radioactive source and directed towards the gold foil.

Expected observations:
Based on the plum pudding model of the atom proposed by J.J. Thomson, it was expected that the alpha particles would pass straight through the gold foil with little or no deflection. According to this model, the positive charge and mass of the atom were believed to be uniformly distributed throughout the atom.

Actual observations:
Contrary to the expectations, the experimental observations showed that most of the alpha particles passed through the gold foil with little deflection, but a small fraction of them were deflected at large angles, and a few even rebounded backward.

Explanation of the observations:
The observations of the alpha scattering experiment could be explained by the following factors:

1. Most of the space in the atom is occupied:
- This option is incorrect because the observations showed that most of the alpha particles passed through the gold foil with little deflection. This implies that most of the space in the atom is empty, allowing the alpha particles to pass through without any significant interaction.

2. All the positive charge and mass of the atom is concentrated in small volume:
- This option is correct. The deflection and rebound of the alpha particles can be explained by the presence of a small, dense, and positively charged nucleus at the center of the atom.
- The observations showed that a small fraction of the alpha particles experienced significant deflection or rebound. This can be attributed to the repulsion between the positively charged alpha particles and the positively charged nucleus of the atom.
- The deflection of the alpha particles indicated that the positive charge and mass of the atom are concentrated in a small volume, which is now known as the nucleus.

3. The mass of the atom is concentrated in the center:
- This option is incorrect as the mass of the atom is distributed between the nucleus and the negatively charged electrons surrounding it.
- The deflection of the alpha particles indicated that the positive charge and mass of the atom are concentrated in a small volume at the center of the atom, which is the nucleus.

4. Positive charge of the atoms very little space:
- This option is incorrect as the observations showed that a small fraction of the alpha particles experienced significant deflection or rebound, indicating the presence of a concentrated positive charge in a small volume at the center of the atom.

Conclusion:
Based on the observations of the alpha scattering experiment, the correct answer is option 'B' - All the positive charge and mass of the atom is concentrated in a small volume. This observation provided evidence for the nuclear model of the atom, where the positive charge and most of the mass are concentrated in

Ans is d
the mass of the atom is concentrated in a very small volume.
that's why rebounded
deflection is due to both alpha and nucleus being positively charged