Hint: The element is a member of the chalcogen group of the periodic table. It is a highly reactive non-metal which reacts with most of the elements of the periodic table. It is gaseous in nature and helps in the breathing process of plant and animal kingdom. Priestly discovered this element. Complete step by step answer: > Electronegativity is the tendency of an atom to attract a shared pair of electrons towards itself. >It increases across a period from left to right because of the increase of the number of charges on the nucleus which results in stronger bonding of electron pairs. > It decreases down a group from top to bottom due to the increasing distance between the nucleus and the valence shell, thereby decreasing the attraction of an electron pair. So, following this trend oxygen is the most electronegative element among the given options in the question due to its position in the periodic table. Among them, it is the farthest element across a period and topmost element across a group with an atomic number 8. > Electronegativity value of oxygen in the Pauling scale is 3.44. The electronegativity trend of atom, cation and anion is: cation < atom < anion This is due to the increased nuclear charge on the anion rather than cation and atom, thereby increasing its tendency to attract electron pairs more. So, the correct option is D.
Note: Electronegativity value of iodine is 2.66. Fluorine is the most electronegative element in the periodic table due to its position in the periodic table and its electronic configuration with seven electrons in its valence shell.