JEE Main 2016 — S Block Elements Question with Solution
From: JEE Main 2016 (Offline)
Question
Choose an option
Show full solutionCorrect option: C
Step-by-step explanation
The first ionization energy is the energy required to remove the most loosely held electron from an atom or a cation. It is measured in units of electron volts (eV) or kilojoules per mole (kJ/mol).
Among the given options, Scandium (Sc) has the highest first ionization energy because it has the smallest atomic radius and the highest nuclear charge. As we move from left to right across a period in the periodic table, the atomic radius decreases while the nuclear charge increases. This results in a stronger attraction between the positively charged nucleus and the negatively charged electrons in the outermost energy level, which requires more energy to remove the most loosely held electron.
The first ionization energy of the given options in increasing order is:
Na < K < Rb < Sc
Therefore, Scandium (Sc) has the highest first ionization energy among the given options.
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This is a previous-year question from JEE Main 2016, covering the S Block Elements chapter of Chemistry. PrepSharp catalogues every PYQ from JEE Main with a verified answer key and step-by-step solution prepared by IIT alumni — so you can search by chapter, topic or year and revise efficiently.