Who was the first scientist to propose that an object could emit only certain amounts of energy?

a) planck
b) einstein
c) bohr
d) rydberg
d) de broglie

Explanation:

The first scientist to propose that an object could emit only certain amounts of energy was Max Planck.

Incandescent (very hot) objects emit different color of lights, i.e. different wavelengths, but by 1900 it was believed that the light (energy) was emitted in a continuous way.

Since the wave model did not explain the emission of such specific wavelengths, when the German physicist Max Planck (1858 - 1947) studied the light emitted by incandescent objects, he proposed that the objects (the matter) could gain or lose energy only in small specific amounts or packages of energy called quanta (plural of quantum).

Planck, later, established the mathematical relation between the energy  of a quantum of light with the frequency of such the radiation (light emitted). This is the formula:

Where, E is the energy, h is Planck's constant, and ν is the frequency.