Question

Pb has an atomic mass of 82. If an atom of that element has an atomic mass of 80, that atom is known as 

A. magnetic.  B. a stereoisomer.  C. radioactive.  D. an isotope. ​

Answer 1

B. And isotope

Explanation

Isotopes are atoms that have the same number of protons but different numbers of neutrons in the nucleus.

For a given element, its isotopes have

the same number of protons

different numbers of neutrons

the same number of electrons

By changing the number of neutrons in the atom of Pb, the Atomic mass will decrease. In this case, the atom of Pb has 2 neutrons less than than Pb itself

Answer 2

Answer: D. an isotope. ​

Step-by-step explanation:

Magnetic is a substance possessing an extraordinary power or ability to attract.

A Stereo isomer is each of one or more compounds which have the same molecular formula but have different three-dimensional orientations of their atoms in space.

Radioactive is a substance which is less stable and thus decomposes to a stable nuclei by releasing some radiations or particles like alpha, beta particles or gamma-radiations.

Isotopes are atoms of same element with same atomic number thus contain same number of protons but different mass number, thus contain different number of neutrons.