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IGNOU MCH-11 (January 2024 – December 2024) Assignment Questions
1. a) Give the trends in metallic radii of alkali, alkaline earth and transition metals of fourth, fifth and sixth periods with proper illustration.
b) Explain periodic variation of electronegativity with atomic number for the first six rows of the periodic table.
2. a) What are the possible molecular structures of xenon hexafluoride? Explain with suitable figures. Explain the geometrical isomers of Ma2b2cd complex with suitable figures.
b) With suitable illustration explain the theory of Craig and Paddock for π bonding in phosphazenes. Give some synthetic routes for polyphosphazenes.
3. a) Explain the concept of hapticity giving suitable examples.
b) What is β-elimination in organometallic chemistry? What is the role of agnostic alkyls in β-elimination?
4. a) With suitable examples explain fluxional organometallic compounds. What are the probable of symmetric and semibridging carbonyls. Give suitable examples.
b) Determine the number and symmetry designations of the infrared-active C-O modes in the following derivatives of Mo(CO)6.
Mo(CO)5PR3 cis-Mo(CO)4 (PR3)2
trans-MO(CO)4 (PR3)2 fac-Mo(CO)3 (PR3)3
5. a) With the help of molecular orbital theory explain the geometry of the nitrosyl ligand.
b) What are the polydentate phosphines? How do you prepare molybdenocene.
6. a) Give the structures of 
b) What are Wade’s Rule? Apply them to any metalloborane.
7. a) Explain the different types of compounds having multiple metal-metal bonds.
b) If pairing energy P for Fe3+ ion is 29,875 cm-1 and ∆O for [Fe (H2O)6]3+ is 13,700 cm-1, find out
(i) whether the complex is high spin or low spin
(ii) the number of unpaired electrons
(iii) whether the complex is coloured or not?
8. a) Give the octahedral as well as tetrahedral field electronic configuration for Cr3+ and Co3+ ions. Which site will be preferred by these ions, octahedral or tetrahedral? Justify your answer.
b) Explain the Curie Law and Curie-Weiss Law along with their plots.
9. a) With suitable illustration explain the super exchange mechanism in d-metal complexes.
b) Write the Russell-Saunders terms symbols for states with the angular momentum quantum numbers 
10. a) [FeF6]3- is almost colourless whereas [CoF6]3- is coloured and exhibits only a single band in the visible region of the spectrum. Justify.
b) Explain charge transfer spectra with suitable examples. What is the reason for the deep purple colour of the permanganate ion?
