Question

Assertion :The free gaseous Cr atom has six unpaired electrons.
Reason : Half-filled s-orbital has greater stability.

• A. Both Assertion and Reason are true and Reason is the correct explanation of Assertion
• B. Both Assertion and Reason are true but Reason is not the correct explanation of Assertion
• C. Assertion is true but Reason is false
• D. Both Assertion and Reason are false

Answer 1

Answer: (C)

The free gaseous $Cr$ atom has six unpaired electrons due to following electronic configuration $($ atomic number $=24)$ $=[ Ar ] 3 d^{5} 4 s^{1}$. This is because half-filled $d$ -orbital is more stable as compared to incompletely filled $d$ -orbital. So, one electron jumps from $4 s^{2}$ -orbital to $3 d$ - orbital.