Among $V(CO)_6$,$Cr(CO)_5$,$Cu(CO)_3$,$Mn(CO)_5$,$Fe(CO)_5$,$[Co(CO)_3]^{3-}$,$[Cr(CO)_4]^{4-}$,and $Ir(CO)_3$,the total number of species isoelectronic with $Ni(CO)_4$ is. . . . . [Given atomic number : $V=23$,$Cr=24$,$Mn=25$,$Fe=26$,$Co=27$,$Ni=28$,$Cu=29$,$Ir=77$ ]

Which one of the following does not follow Sidgwick $EAN$ rule?

Which of the following complexes does the central metal ion $NOT$ obey the $EAN$ rule? (Atomic numbers: $Pt=78, Cu=29, Zn=30, Fe=26$)

$a$. Answer the following questions:
$i$. Which element of the first transition series has the highest second ionisation enthalpy?
$ii$. Which element of the first transition series has the highest third ionisation enthalpy?
$iii$. Which element of the first transition series has the lowest enthalpy of atomisation?
$b$. Identify the metal and justify your answer:
$i$. Carbonyl $M(CO)_5$
$ii$. $MO_3F$

The $EAN$ of metal atoms in $Fe(NO)_2(CO)_2$ and $Co_2(CO)_8$ respectively are

The Effective Atomic Number $(EAN)$ of $Co$ in $[Co(NH_3)_6]^{3+}$ is: