Write down the electronic configuration of:
$(i) Cr^{3+}$
$(ii) Pm^{3+}$
$(iii) Cu^{+}$
$(iv) Ce^{4+}$
$(v) Co^{2+}$
$(vi) Lu^{2+}$
$(vii) Mn^{2+}$
$(viii) Th^{4+}$

$(i) Cr^{3+}: [Ar]^{18} 3d^{3}$
$(ii) Pm^{3+}: [Xe]^{54} 4f^{4}$
$(iii) Cu^{+}: [Ar]^{18} 3d^{10}$
$(iv) Ce^{4+}: [Xe]^{54}$
$(v) Co^{2+}: [Ar]^{18} 3d^{7}$
$(vi) Lu^{2+}: [Xe]^{54} 4f^{14} 5d^{1}$
$(vii) Mn^{2+}: [Ar]^{18} 3d^{5}$
$(viii) Th^{4+}: [Rn]^{86}$