The answer is B. Isotopes.
Isotopes are atoms of the same element that have different numbers of neutrons. They have the same number of protons, which determines the chemical element, but different numbers of neutrons, which determine the isotope.
The number of protons and neutrons in the nucleus of an atom is called the atomic mass number.For example, carbon-12 has 6 protons and 6 neutrons, while carbon-14 has 6 protons and 8 neutrons. Both carbon-12 and carbon-14 are isotopes of carbon, but they have different atomic mass numbers.
Isotopes are important in many fields, including chemistry, physics, and biology. They are used in nuclear power plants, medical imaging, and research.
A. Isobars are atoms of different elements that have the same mass number. For example, carbon-12 and oxygen-16 are both isobars.
C. Isotones are atoms of different elements that have the same number of neutrons. For example, carbon-12 and nitrogen-14 are both isotones.
D. Isomers are molecules that have the same chemical formula but different structures. For example, ethane and ethene are both isomers of C2H6.