The official web site of the nobel prize explains that marie curie’s chemistry prize was partly for her discovery that the radioactivity of a substance is unaffected when it undergoes a chemical reaction. what does this discovery imply?

radioactivity involves all particles that make up an atom.
radioactivity involves the particles that make up an atom’s nucleus.
radioactivity involves only neutrons.
radioactivity involves only the electrons in an atom’s electron cloud.

D) Radioactivity involves only the electrons in an atoms electron cloud

D) Radioactivity involves only the electrons in an atoms electron cloud

the role of the microscope world in creating new materials .

"among the transition metal elements, manganese and zinc have a slight lowering of electronegativities. the reason behind this is that the nuclear charges of these elements are slightly weaker than the other transition metal elements due to the way their valence electrons are filled up. both manganese and zinc have their valence electrons filled up to the 4th shell with 1 pair of electrons (4s2) completely occupying it. although the electrons in the 3rd shell (3d) are yet to be paired since the outer most shell is filled up, the ability of the nucleus to attract electrons is lessened. hence,   the electronegativity (or the ability to attract electrons) is lessened."