Which is the correct formula of the Wilkinson catalyst?

Which of the following are organometallic compounds? $(1)$ Grignard reagent $(2)$ Sodium methoxide $(3)$ Trimethylboron $(4)$ $Al_2(CH_3)_6$

What is the name of the complex formed by the coordination reaction of carbon monoxide?

Assertion : $C-O$ bond in metal carbonyls is long.
Reason : There is delocalisation of electrons from filled $d$ orbitals into the empty $\pi^*$ orbitals on the $CO$ ligands.

In Zeise's salt,the central metal atom acts as:

Which of the following is not considered as an organometallic compound?