Assertion : Boron has a smaller first ionisation enthalpy t…

Chemistry Classification of Elements and Periodicity Telangana & AP CET Previous Year Question Single Correct MCQ

Published on: August 14, 2026

Assertion : Boron has a smaller first ionisation enthalpy than beryllium.
Reason : The penetration of a -electron to the nucleus is more than the -electron hence, -electron is more shielded by the inner core of electrons than -electrons.

Assertion and Reason both are correct statements but Reason is not correct explanation for Assertion.

Assertion is correct statement but Reason is wrong statement.

Assertion and Reason both are correct statements and Reason is correct explanation for Assertion

Assertion and Reason both are wrong statements.

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Electronic configuration of boron ; [He] . First ionisation will take place from unpaired -electron. -electron of experience lesser nuclear attractive force for ionisation. Removal of electron takes place from paired electrons which requires more energy. Electronic configuration of .