Statement A: The electrons present outside the nucleus revolve around the nucleus with high velocities. 

Statement B: The entire positive charge and mass of the atom is concentrated in the small, central part known as the nucleus. 

According to Rutherford, the entire positive charge and mass of the atom are concentrated in the small, central part known as the nucleus. Atoms have empty space, and the electrons present outside the nucleus revolve around the nucleus with high velocities.