Q.In a Bainbridge mass spectrometer positive rays of the same element produce different traces. The traces correspond to :

Nuclei of different elements, or different forms of the same element, can be compared and classified along three distinct axes, depending on which of $Z$ (atomic number), $A$ (mass number) or $N$ (neutron number) they happen to share:

Isotopes share the same atomic number $Z$ but differ in mass number $A$ - the same element, but with different numbers of neutrons. Hydrogen provides the classic example: $^{1}_{1}H$ (ordinary hydrogen, 0 neutrons), $^{2}_{1}H$ (deuterium, 1 neutron) and $^{3}_{1}H$ (tritium, 2 neutrons) are all isotopes of hydrogen, each with exactly one proton. Since chemical behaviour is governed by the number of electrons (equal to $Z$), every isotope of a given element shares essentially identical chemical properties and occupies the very same single position in the periodic table, regardless of how many neutrons it carries; only the isotope's mass (and, for unstable isotopes, its nuclear stability) differs. Carbon's four naturally occurring isotopes ($^{11}C$, $^{12}C$, $^{13}C$, $^{14}C$) illustrate how unevenly isotopes can be distributed in nature - about 98.9% of natural carbon is $^{12}C$, only 1.1% is $^{13}C$, and a mere $0.0001\%$ is the radioactive isotope $^{14}C$ used in carbon dating. …