JEE Main 2019ChemistryClassification of Elements and Periodicity in PropertiesMediumMCQ

JEE Main 2019Classification of Elements and Periodicity in Properties Question with Solution

JEE Main 2019 (12 Apr Shift 2)

Question

In comparison to boron, berylium has:

Choose an option

Show full solutionCorrect option: B
Correct answer
Blesser nuclear charge and greater first ionisation enthalpy

Step-by-step explanation

Electronic configuration of Be =1s2 2s2
Electronic configuration of B =1s2 2s2 2p1
Due to full-filled configuration of Beryllium, it has higher first ionization energy.
Effective nuclear charge
Zeff of Be =4-σ=4-2×0.85+0.35×1=2.05
Zeff of B =5-σ=5-2×0.85+0.35×2=2.6
Zeff of B > Zeff of Be

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About this question

This is a previous-year question from JEE Main 2019, covering the Classification of Elements and Periodicity in Properties 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.