The number of protons in one atom of an element determines the atom's , and the number of electrons determines of an element.

The number of protons in one atom of an element determines the atom’s identity and the number of electrons determines electrical charge of an element.

Explanation:

Atoms are made up of protons, neutrons and electrons. The protons and neutrons are enclosed in a specific spherical region at the center of the atom termed as nucleus of the atom. This is because proton is positive charge and neutron is neutral charged high mass particles.

While the electrons are negative charged lighter mass particles. So the electrons will revolve around the nucleus. The protons number in element's one atom helps to identity its chemical properties of the element. While the electrons number in an element will determine the electrical charge and conducting nature of the element.

.) the observation by semmelweis that more mothers died of childbed fever when their doctors also worked in the morgue

the answer is b, have negligible mass