The idea that atoms radiate energy only when their electrons move from higher to lower energy levels was first advanced by:

a) J. J. Thomson Niels

b) Bohr Ernest Rutherford

c) Albert Einstein

d) Christian Doppler

b) Bohr - Ernest Rutherford

Explanation:

The Bohr - Ernest Rutherford model was system described by two physicists: Niels Bohr and Ernest Rutherford.

Rutherford was the first person to describe the nucleus of the atom as a tiny and positively-charged core and to state that the atom's mass was located within the nucleus.

After these important findings and after performing multiple experiments, Bohr suggested that the energy of an atom's electron is dependant on the size of its orbit. This lead to the hypothesis that, in an atom, its radiation is emitted when an electron moves from a high energy orbit to a lower energy orbit level, which was then proved and called the "quantum atomic theory."