Question 3
What did Niels Bohr add to Rutherford's model?
The right answer is the one marked above.
Bohr said the electrons move around the positively charged nucleus in definite paths — orbits. They do not move just anywhere around it.
The nucleus, and its positive charge, came from Rutherford's model in 1911. Bohr's contribution was the word definite — and that is what leads to shells, energy levels, and everything in section 3.2.