Answer
a) $K_{2}[Pt(NO_{2})_{4}]$
The central metal ion is Platinum(Pt) and it is in a $+2$ oxidation state.
b) $[Co(NO_{2})_{3}(NH_{3})_{3}]$
The central metal ion is cobalt(Co) and it is in a $+2$ oxidation state.
c) $[Ag(NH_{3})_{2}]I$
The central metal ion is silver(Ag) and it is in a $+1$ oxidation state.
d) $K_{4}[Ni(CN)_{6}]$
The central metal ion is Nickel(Ni) and it is in a $+2$ oxidation state.
e) $[Ni(NH_{3})_{4}(H_{2}O)_{2}](NO_{3})_{2}$
The central metal ion is Nickel(Ni) and it is in a $+2$ oxidation state.
f) $Na[Al(H_{2}O)_{2}(OH)_{4}]$
The central metal ion is Aluminium(Al) and it is in a $+3$ oxidation state.
Work Step by Step
a) $K_{2}[Pt(NO_{2})_{4}]$
The central metal ion is Platinum(Pt) and it is in a $+2$ oxidation state.
b) $[Co(NO_{2})_{3}(NH_{3})_{3}]$
The central metal ion is cobalt(Co) and it is in a $+2$ oxidation state.
c) $[Ag(NH_{3})_{2}]I$
The central metal ion is silver(Ag) and it is in a $+1$ oxidation state.
d) $K_{4}[Ni(CN)_{6}]$
The central metal ion is Nickel(Ni) and it is in a $+2$ oxidation state.
e) $[Ni(NH_{3})_{4}(H_{2}O)_{2}](NO_{3})_{2}$
The central metal ion is Nickel(Ni) and it is in a $+2$ oxidation state.
f) $Na[Al(H_{2}O)_{2}(OH)_{4}]$
The central metal ion is Aluminium(Al) and it is in a $+3$ oxidation state.
