Answer: The empty space in the nucleus let the particles pass through without any deflection.
Step-by-step explanation:
Rutherford gave an experiment which is known as gold foil experiment.
In this experiment, he took a gold foil and bombarded it with the alpha particles that carries positive charge of 2 units. He expected that the particles will pass straight through the foil, but to his surprise, some of them deflected their path and a few of them bounced back.
From this he gave a result that an atom consist of empty space and also has a small positive charge which is present at the center. Due to this positive charge, the alpha particles deflected their path and some of them bounced straight back from their path.
As, the atom consist of alot of empty space. Thus, the alpha particles passed straight through without any deflection.