Which 2 + ion has two 3d electrons? which has eight 3d electrons?

1) Titanium cation has two 3d electrons.

₂₂Ti 1s²2s²2p⁶3s²3p⁶3d²4s².

₂₂Ti²⁺1s²2s²2p⁶3s²3p⁶3d²4s⁰.

2) Nickel cations has eight 3d electrons.

₂₈Ni 1s²2s²2p⁶3s²3p⁶3d⁸4s².

₂₈Ni²⁺ 1s²2s²2p⁶3s²3p⁶3d⁸4s⁰.

Both cations (titanium and zinc) lost two electrons from 4s orbital, because 4s orbital is far away from nucleus.