Is co have 4 unpaired electron

Co (cobalt) has 3 unpaired electrons

Reason: The ground state electron configuration is [Ar]3d^7 4^2. The 3d sublevel have five orbitals , each of which can contain two electrons with opposite sppin for a total 10. However, when adding electronsto the orbitals within a sublevelone electron will be added to each orbital  and each with the same spin , after which additional electrons will be added with a maximum of two, each having an opposite spin.

So, if we look at the ground state electron configuration of cobalt, we see that the 3d sublevel is not full. There are two d orbbitals having paired electrons with opposite spin. and three d orbitals having one unpaired electron, each with the same spin

HELLO BHAWANA

The ground state electron configuration is [Ar]3d742. The 3d sublevel has five orbitals, each of which can contain two electrons with opposite spin (Pauli exclusion principle) for a total of 10.

However, when adding electrons to the orbitals within a sublevel, one electron will be added to each orbital, and each with the same spin (Hund's rule), after which additional electrons will be added with a maximum of two, each having an opposite spin. (Pauli exclusion principle).

So if we look at the ground state electron configuration of cobalt, we see that the 3dsublevel is not full. There are two d orbitals having paired electrons with opposite spin, and three d orbitals having one unpaired electron, each with the same spin.

hi there Bhawana,

The ground state electron configuration of Cobalt indicates that its 3d sublevel has five orbitals where each can only contain 2 electrons with reverse rotation.but as the 3d sublevel is not completely full hence 2d orbitals combine with electrons of opposite rotation and the 3d orbital is left with one unpaired electron.

so in total Co has 3 unpaired electrons.