Consider the following statements with reference to the Periodic Table of chemical elements : I. lonisation potential gradually decreases along a period. II. In a group of elements, electron affinity decreases as the atomic weight increases. III. In a given period, electronegativity decreases as the atomic number increases. Which of these statement(s) is/are correct ?

Option 2 is correct. Statement I is false: ionisation potential (ionization energy) generally increases across a period (left to right) because effective nuclear charge rises and atomic radius falls, so it does not “gradually decrease” along a period . Statement II is true: down a group atomic weight and principal quantum number increase, and electron affinity generally decreases in magnitude (becomes less negative), so affinity for an added electron falls as atomic weight increases in the group [1]. Statement III is false: electronegativity increases across a period (left to right) as nuclear attraction for bonding electrons strengthens, not decreases with increasing atomic number in a given period [1].

Sources

1. [1] https://www.acs.org/content/dam/acsorg/education/students/highschool/chemistryclubs/infographics/mastering-periodic-trends-infographic.pdf