- 1. Which metal is at the center of the Vitamin B12 molecule?
A) Copper
B) Iron
C) Nickel
D) Cobalt
- 2. What is the solubility of Vitamin B12?
A) Soluble in oil
B) Insoluble in water
C) Fat-soluble
D) Water-soluble
- 3. Vitamin B12 is involved in the synthesis of which of these?
A) Nucleic acid
B) Lipids
C) Glucose
D) Proteins
- 4. What is the primary dietary source of Vitamin B12?
A) Leafy green vegetables
B) Root vegetables
C) Offal or meat of herbivorous animals
D) Grain products
- 5. What color are Dicobalt octacarbonyl crystals?
A) Orange-red
B) Deep blue
C) Bright yellow
D) Emerald green
- 6. Dicobalt octacarbonyl reacts with hydrogen to form which compound?
A) Co(CO)6
B) H2Co(CO)8
C) HCo(CO)4
D) Co(CO)3
- 7. Which reaction is catalyzed by Dicobalt octacarbonyl?
A) Carbonylation
B) Fermentation
C) Photosynthesis
D) Polymerization
- 8. How many valence electrons does Cobaltocene have?
A) 17
B) 19
C) 18
D) 20
- 9. Cobaltocene is a structural analog to which compound?
A) Manganocene
B) Nickelocene
C) Chromocene
D) Ferrocene
- 10. What is the stable electron count of the oxidized Cobaltocene product (Co(C5H5)+2)?
A) 18
B) 19
C) 16
D) 17
- 11. Compared to ferrocene, how sensitive is Cobaltocene to oxidation?
A) Much less sensitive
B) Equally sensitive
C) Much more sensitive
D) Completely inert
- 12. What is the chemical formula of Dicobalt octacarbonyl?
A) Co2(CO)4
B) Co(CO)4
C) Co2(CO)8
D) Co(CO)8
- 13. Cobaltocene is a complex of cobalt and which organic compound?
A) Methane
B) Ethylene
C) Benzene
D) Cyclopentadiene
- 14. Which biological function is Vitamin B12 involved in?
A) Oxidation
B) Methylation
C) Reduction
D) Calcification
- 15. What forms when Dicobalt octacarbonyl reacts with sodium?
A) Na2Co(CO)8
B) NaCo(CO)8
C) NaCo(CO)4
D) Co(CO)4Na2
- 16. What is the color of the hexaaquocobalt(II) complex [Co(H2O)6]2+?
A) Yellow-gold
B) Blue
C) Pink
D) Green
- 17. Which ligand is found in the green triscarbonatocobaltate(III) anion?
A) Ammonia
B) Oxalate
C) Carbonate
D) Chloride
- 18. Which ligands help stabilize the high Co4+ and Co5+ oxidation states?
A) Oxide and fluoride
B) Ammonia and water
C) Carbonate and nitrite
D) Chloride and oxalate
- 19. Which Nobel-prize winning pioneer worked with [Co(NH3)6]3+?
A) Linus Pauling
B) Alfred Werner
C) Ernest Rutherford
D) Dmitri Mendeleev
- 20. What type of ligands are generally favored by Co3+ complexes?
A) Sulfate ligands
B) Phosphine ligands
C) Borane ligands
D) Ammine ligands
- 21. What is the coordination number of the central cobalt atom in cobalt(III) hexammine chloride?
A) Four
B) Six
C) Eight
D) Three
- 22. Which ligand is used in the complex trisoxalatocobaltate(III)?
A) Nitrite
B) Hydroxide
C) Oxalate
D) Carbonate
- 23. What is the formula for tetrachloridocobaltate(II)?
A) [Co(CO3)3]3-
B) [CoCl4]2-
C) [Co(en)3]3+
D) [Co(H2O)6]2+
- 24. What is the color of anhydrous cobalt(II) chloride?
A) Blue
B) Pink
C) Magenta
D) Green
- 25. What color is cobalt(II) bromide?
A) Pink
B) Magenta
C) Green
D) Blue
- 26. Which substance is manufactured using color-changing cobalt(II) chloride?
A) Plastic
B) Glass
C) Ceramics
D) Silica gel
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