Question

oppositely charged objects attract each other. this attraction holds electrons in atoms and holds atoms to one another in many compounds. however, ernest rutherfords model of the atom failed to explain why electrons were not pulled into the atomic nucleus by this attraction. what change to the atomic model helped solve the problem seen in rutherfords model? bohrs work with atomic spectra led him to say that the electrons were limited to existing in certain energy levels, like standing on the rungs of a ladder. bohrs work with cathode rays led him to say that the electrons were located within the mass of positive material, like plums in a pudding. thomsons work with cathode rays led him to say that the electrons were located within the mass of positive material, like plums in a pudding. thomsons work with atomic spectra led him to say that the electrons were limited to existing in certain energy levels, like standing on the rungs of a ladder.

Explanation:

Bohr's model improved on Rutherford's by suggesting electrons exist in discrete energy levels. Thomson's 'plum - pudding' model is different and not related to solving Rutherford's model problem. Bohr worked with atomic spectra, not cathode rays, to propose energy - level concept.

Answer:

A. Bohr's work with atomic spectra led him to say that the electrons were limited to existing in certain energy levels, like standing on the rungs of a ladder.