How many outer-shell d electrons are there in each of the transition-metal ions?Mn(IV) :Co(III) :Fe(II) :Ni(II) :

Mn(IV): 3 outer-shell d electrons

Co(III): 6 outer-shell d electrons

Fe(II): 6 outer-shell d electrons

Ni(II): 8 outer-shell d electrons

Explanation:

Mn(IV):

The ion is Mn⁴⁺, so it has lost 4 valence electrons. The ground state electronic configuration of Mn is [Ar]3d ⁵ 4s ². When the neutral atom loses 4 electrons, the electronic configuration is [Ar]3d ³.

outer-shell d electrons = 3

Co(III):

The ion is Co³⁺, so it has lost 3 valence electrons. The ground state electronic configuration of Co is [Ar]3d ⁷4s ². When the neutral atom loses 3 electrons, the electronic configuration is [Ar]3d ⁶.

outer-shell d electrons = 6

Fe(II):

The ion is Fe²⁺, so it has lost 2 valence electrons. The ground state electronic configuration of Fe is [Ar]3d ⁶4s ². When the neutral atom loses 2 electrons, the electronic configuration is [Ar]3d ⁶.

outer-shell d electrons = 6

Ni(II):

The ion is Ni²⁺, so it has lost 2 valence electrons. The ground state electronic configuration of Ni is [Ar]3d ⁸4s ². When the neutral atom loses 2 electrons, the electronic configuration is [Ar]3d ⁸.

outer-shell d electrons = 8

elements make up everything, and they combine to make compounds.

the answer is c