Q.Explain the trend of the following in group 13 elements :
electron affinity

Step 1. Note the data limitation. This chapter's own tables (9.2) give atomic radius, ionic radius, ionization enthalpy, electronegativity, density and melting/boiling point for group 13, but do not print electron-affinity values, so no in-text figures can be cited for this trend.

Step 2. Apply the standard periodic-chemistry reasoning (general knowledge, not from this chapter's source). Electron affinity is the energy released when an atom gains an electron. Down a group, atomic size generally increases, which would normally make electron affinity less negative (weaker attraction for an extra electron) — but the very first member of a group (here, boron) often has an anomalously small electron affinity of its own, because its outer 2p orbital is so compact that the incoming electron experiences unusually strong repulsion from the electrons already there. …

Using standard, well-established periodic-trend reasoning for electron affinity, since this chapter's own source tabl …

• Asserting specific numeric electron-affinity values as if they came from this chapter's tables, when …