Final answer:
Argon, being a noble gas, would not typically have an assigned electronegativity. If we are considering only elements with an assigned electronegativity value, Calcium would have the lowest electronegativity out of the listed elements because it is an alkaline earth metal located further to the left on the periodic table.
Step-by-step explanation:
The question asks about electronegativity, which is a measure of the tendency of an atom to attract a bonding pair of electrons. Based on the provided choices, we need to determine which element has the smallest electronegativity. However, the choices given within the question (Calcium, Argon, Hydrogen, and Bromine) do not match the elements listed for reference in the additional information. From the provided list, we know that cesium has the lowest electronegativity of nonradioactive elements, and noble gases typically do not have electronegativity values because they do not readily form bonds. Therefore, to identify the element with the smallest electronegativity among the given choices, we would consider the position of the elements on the periodic table and establish trends. In this case, Argon (Ar), being a noble gas, would not typically have an assigned electronegativity because it is inert and does not form bonds, which means it effectively has an electronegativity of zero, the smallest possible value. However, if we are considering only elements that do form bonds and have an assigned electronegativity value, then Calcium (Ca), being an alkaline earth metal, would generally have a lower electronegativity than Hydrogen (H) or Bromine (Br), which are further to the right on the periodic table.