What is the best description of what becquerel observed in his experiment?
a. stable nuclei absorbing high-energy particles as they formed less stable compositions
b. stable nuclei emitting high-energy particles as they formed less stable compositions
c. unstable nuclei absorbing high-energy particles as they formed more stable compositions
d. unstable nuclei emitting high-energy particles as they formed more stable compositions

The answer is: D.unstable nuclei emitting high-energy particles as they formed more stable compositions.

Those high-energy particles are alpha particles , beta particles , gamma radiation.

For example, the decay chain of ²³⁸U is called the uranium series.

Decay start with U-238 and ends with Pb-206. There are several alpha and beta minus decays.

Antoine Henri Becquerel (1852 – 1908) was a French physicist and the first person to discover evidence of radioactivity.

Becquerel wrapped fluorescing crystal (uranium salt potassium uranyl sulfate) in a cloth, along with the photographic plate and a copper Maltese cross.

Several days later, he discovered that a image of the cross appeared on the plate.

The uranium salt was emitting radiation.

Because of this discovery, Becquerel won a Nobel Prize for Physics in 1903, which he shared with Marie Curie and Pierre Curie.

D.unstable nuclei emitting high-energy particles as they formed more stable compositions

tracks, burrows, eggshells, nests, tooth marks, or gastroliths