How many valence electrons does Ni have?
Electron present in valence shell of an atom is called valence electron.
The valence shell is the outermost shell of an atom in its uncombined state, which contains the electrons most likely to account for the nature of any reactions involving the atom and of the bonding interactions it has with other atoms.
Outermost shell of Ni is 4th shell i.e N shell. It contains 2 electrons.
Therefore Ni has 2 valence electrons.