AIIMS 2019 Chemistry Ionization Energy Assertion Reason Question

Option C is correct because the assertion that the first ionization energy of beryllium (Be) is greater than that of boron (B) is true; however, the reason provided is incorrect. Beryllium has a stable electron configuration (1s² 2s²), but its higher ionization energy compared to boron (1s² 2s² 2p¹) is primarily due to its smaller atomic radius and increased effective nuclear charge, which leads to stronger attraction between the nucleus and the outermost electron.

Option A is incorrect because, while the assertion is true, the reason does not accurately explain the phenomenon. Option B is also incorrect because it claims that the reason is not the correct explanation when, in fact, it is incorrect altogether. Option D is incorrect as the assertion is indeed correct.