An example of a sigma bonded organometallic compound is:

1.	Grignard's reagent	2.	Ferrocene
3.	Cobaltocene	4.	Ruthenocene

The correct increasing order of trans-effect of the following species is:

1.  ${\mathrm{NH}}_3>{\mathrm{CN}}^{-}>\mathrm{Br}>{\mathrm{C}}_6{\mathrm{H}}_5^{-}$

2.  ${\mathrm{CN}}^{-}>{\mathrm{C}}_6{\mathrm{H}}_5^{-}>{\mathrm{Br}}^{-}>{\mathrm{NH}}_3$

3.  ${\mathrm{Br}}^{-}>{\mathrm{CN}}^{-}>{\mathrm{NH}}_3>{\mathrm{C}}_6{{\mathrm{H}}^{-}}_5$

4.  ${\mathrm{CN}}^{-}>{\mathrm{Br}}^{-}>{\mathrm{C}}_6{{\mathrm{H}}^{-}}_5>{\mathrm{NH}}_3$

Iron carbonyl, $\mathrm{Fe}{\left(\mathrm{CO}\right)}_5$, is classified as:

The number of possible isomers for the complex $\left[\mathrm{Co}{\left(\mathrm{en}\right)}_2{\mathrm{Cl}}_2\right]Cl$ will be (en=ethylenediamine):

The hybridization involved in the complex ${\left[\mathrm{Ni}{\left(\mathrm{CN}\right)}_4\right]}^{2-}$is:
(Atomic number of Ni=28)

An ion, among the following, that has a magnetic moment of 2.84 BM is:
(At. no. Ni = 28, Ti = 22, Cr = 24, Co = 27)

1. Ni²⁺
2. Ti³⁺
3. Cr²⁺
4. Co²⁺

Cobalt(III) chloride forms several octahedral complexes with ammonia.
A compound among the following that does not give a test for chloride ions with silver nitrate at 25 °C is: