$(P)\, Fe(CO)_5\,\,\, (Q)\,CO\,\,\, (R)\, H_3B \leftarrow CO\,\,\,(S)\, [Mn(CO)_5]^-$
Correct sequence of \(CO\) bond order:
\(\underset{(CO\,bond\,order\,>\,3.0)}{\mathop{{{H}_{3}}B\leftarrow CO}}\,>\underset{B.O.=3.0}{\mathop{CO}}\,>\underset{CO\,bond\,order\,<3.0}{\mathop{Fe{{(CO)}_{5}}}}\,>\underset{(CO\,bond\,order\,<3.0)}{\mathop{{{[Mn{{(CO)}_{5}}]}^{-}}}}\,\)
$(I)\, [(Ph_3P)_2PdCl_2PdCl_2]$ $(II)\,[NiBrCl(en)]$
$(III)\, Na_4 [Fe(CN)_5 NOS]$ $(IV)\, Cr(CO)_3(NO)_2$
$(I)\,-\,(II)\,-\,,(III)\,-\,(IV)$
સંકીર્ણ $-$ નામ