NEET ChemistryClass 11Stability of half-filled and fully filled orbitalsMediumAssertion–Reason

Chromium breaks the simple aufbau filling order in its ground state. Judge the Assertion (A) and the Reason (R) below.

Assertion (A): The ground-state configuration of chromium (Z = 24) is [Ar]3d⁵4s¹ rather than [Ar]3d⁴4s².
Reason (R): Exactly half-filled subshells are extra stable because of their symmetrical distribution and larger exchange energy.

More NEET Chemistry chapters

Chemical Bonding and Molecular Structure9 questions Classification of Elements and Periodicity in Properties10 questions Equilibrium9 questions Hydrocarbons10 questions

© 2026 Lumi (Aikolumi Software Pvt Ltd). Original questions written by Lumi. Free to view and practise on this site. Copying, republishing or reproducing these questions, options or solutions, in print or online, is not permitted.

Chromium breaks the simple aufbau filling order in its ground state. Judge the Assertion (A) and the Reason (R) below.

Practising is step one. Knowing what to practise next is the hard part.