JEE Main 2023Chemistrys Block ElementsMediumNumerical

JEE Main 2023 — s Block Elements Question with Solution

JEE Main 2023 (31 Jan Shift 2)

Question

The number of alkali metal(s), from Li, K, Cs, Rb having ionization enthalpy greater than 400 kJ mol-1 and forming stable super oxide is

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Show full solutionCorrect answer: 2
Correct answer
2

Step-by-step explanation

The super oxide O2- ion is stable only in the presence of large cations K,Rb,Cs. K,Rb have IE1>400 kJ/mol from the table below. Ionisation enthalpy decreases down the group as metallic character increases.
 

Metal Li Na K Rb Cs
IE(KJ/mol) 520 496 419 403 376

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About this question

This is a previous-year question from JEE Main 2023, 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.