Consider the following statements with reference to the periodic table of chemical elements:

Correct Option (b):

Statement 2 is correct. In a group of elements, as one moves down, the atomic number and atomic weight increase. Concurrently, the number of electron shells increases, leading to a larger atomic size and an enhanced shielding effect from inner electrons. These factors reduce the effective nuclear charge experienced by an incoming electron, thereby decreasing the atom's attraction for an additional electron. Consequently, electron affinity generally decreases down a group.

Incorrect Options:

Statement 1 is incorrect. Ionisation potential (or ionisation energy) generally increases across a period from left to right. This is due to an increase in the effective nuclear charge and a decrease in atomic radius, which results in a stronger attraction between the nucleus and the valence electrons, making it more difficult to remove an electron.

Statement 3 is incorrect. In a given period, electronegativity generally increases as the atomic number increases (from left to right). This trend is attributed to the increasing effective nuclear charge and decreasing atomic radius across the period, which enhances the atom's ability to attract shared electrons in a chemical bond.

Based on the analysis, only statement 2 is correct. Therefore, options (a), (c), and (d) are incorrect.