The number of bridging $CO$ ligand$(s)$ and $Co-Co$ bond$(s)$ in $Co_2(CO)_8$ respectively are

The correct statement$(s)$ regarding the binary transition metal carbonyl compounds is (are) (Atomic numbers: $Fe = 26, Ni = 28$)
$A$. Total number of valence shell electrons at metal centre in $Fe(CO)_5$ or $Ni(CO)_4$ is $16$
$B$. These are predominantly low spin in nature
$C$. Metal-carbon bond strengthens when the oxidation state of the metal is lowered
$D$. The carbonyl $C-O$ bond weakens when the oxidation state of the metal is increased

$Mn_2(CO)_{10}$ is an organometallic compound due to the presence of

Match List-$I$ with List-$II$:

$LIST-I$ (Substances)	$LIST-II$ (Element Present)
$A$. Ziegler catalyst	$I$. Rhodium
$B$. Blood pigment	$II$. Cobalt
$C$. Wilkinson catalyst	$III$. Iron
$D$. Vitamin $B_{12}$	$IV$. Titanium

Choose the correct answer from the options given below:

Which of the following is an organometallic compound?

In $Fe_2(CO)_9$,the two iron atoms are