Final answer:
In Rutherford's experiment, the number of α particles scattered at large angles would decrease as the thickness of the gold foil increases.
Step-by-step explanation:
In Rutherford's experiment, the number of α particles scattered at large angles in the gold foil would decrease as the thickness of the foil increases. This can be understood by considering the nature of Rutherford scattering and the structure of the atom.
During the experiment, Rutherford found that most of the α particles passed through the foil unobstructed. However, a small percentage of α particles were scattered at large angles. This scattering occurred when an α particle came close to the positive charge concentrated in the very small, dense nucleus of the gold atom. The larger the thickness of the gold foil, the less likely it is that the α particles will interact with the nucleus and scatter at large angles.
Therefore, as the thickness of the gold foil increases, the number of α particles scattered at large angles will decrease.