The number of valence electrons present in the metal among Cr, Co, Fe and Ni which has the lowest enthalpy of atomisation is :
- 10
- 6
- 9
- 8
Answer
(2) 6
Solution
As per NCERT, aH ( kJ mol-1): Cr 397, Fe 416, Co 425, Ni 430
Lowest for Cr
Cr (Z = 24): [Ar] 3d5 4s1
Valence electrons = 5 (3d) + 1 (4s) = 6
Answer: (2)