The geometry and magnetic behaviour of the complex [Ni(CO)₄] respectively are:

1. Square planar and diamagnetic.

2. Tetrahedral and diamagnetic.

3. Square planar and paramagnetic.

4. Tetrahedral and paramagnetic.

Which of the following has the longest C ­—O bond length? (Free C—O bond length in CO is 1.128 )

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

The correct statement among the following regarding [Mn(CN)₆]^3-is:

1. It is sp³d² hybridized and tetrahedral.

2. It is d²sp³ hybridized and octahedral.

3. It is dsp² hybridised and square planar.

4. It is sp³d² hybridised and octahedral.

Jahn-Teller effect is not observed in high spin complexes of?

1. d⁷

2. d⁸

3. d⁴

4. d⁹

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

The correct increasing order for the wavelengths of absorption in complexes of Co³⁺ is:

1. [Co(H₂O)₆]³⁺ < [Co(en)₃]³⁺ < [Co(NH₃)₆]^{3 +}

2. [Co(H₂O)₆]³⁺ < [Co(NH₃)₆]³⁺ < [Co(en)₃]³⁺

3. [Co(NH₃)₆]³⁺ < [Co(en)₃]³⁺ < [Co(H₂O)₆]³⁺

4. [Co(en)₃]³⁺ < [Co(NH₃)₆]³⁺ < [Co(H₂O)₆]³⁺

An example of a sigma bonded organometallic compound is: