Which of these statements about [Co(CN)6]3- is true? from Chemi

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 Multiple Choice QuestionsMultiple Choice Questions

171.

Which of the following has longest C-O bond length? (free C-O bond length in CO is 1.128 A0)

  • [Co(CO)4]-

  • [Fe(CO)4]-2

  • [Mn(CO)6]+

  • [Mn(CO)6]+

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172.

Which of the following biphenyls is optically active?

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173.

Which of the following processes does not involve oxidation of iron?

  • Rusting of iron sheets

  • Decolourisation of blue CuSO4 solution by iron

  • Formation of Fe(CO)5 from Fe

  • Formation of Fe(CO)5 from Fe

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174.

Which of these statements about [Co(CN)6]3- is true?

  • [Co(CN)6]3- has no unpaired electrons and will be in a low-spin configuration.

  • [Co(CN)6]3-  has four unpaired electrons and will be in a low-spin configuration

  • [Co(CN)6]3-  has four unpaired electrons and will be in high-spin configuration.

  • [Co(CN)6]3-  has four unpaired electrons and will be in high-spin configuration.


A.

[Co(CN)6]3- has no unpaired electrons and will be in a low-spin configuration.

[Co(CN)6]-3
electronic configuration of Co : 1s2 2s2 2p6 3s2 3p6 3d6.

CN- is a strong field ligand and as it approaches the metal ion, the electrons must pair up. 
The splitting of the d -orbitals into two sets of orbitals in an octahedral [Co(CN6)]3- may be represented as,
 
Here, for d6 ions, three electrons first enter orbitals with parallel spin put the remaining may pay up in t2g orbital giving rise  to low spin complex. 

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175.

Cobalt (III) chloride forms several octahedral complexes with ammonia, which of the following will not give a test for chloride ions with silver nitrated at 250 C? 

  • CoCl. 3NH3

  • CoCl. 4NH3

  • CoCl. 5NH3

  • CoCl. 5NH3

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176.

Among the following complexes, the one which shows zero crystal field stabilisation energy (CFSE) is

  • [Mn(H2O)6]3+

  • [Fe(H2O)6]3+

  • [Co(H2O)6]3+

  • [Co(H2O)6]3+

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177.

Which of the following complexes  is used to be as an anticancer  agent ?

  • mer=[Co(NH3)Cl3]

  • cis-[PtCl2(NH3)2]

  • cis-K2[PtCl2Br2]

  • cis-K2[PtCl2Br2]

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178.

Which of the following compounds will undergo racemization when a solution of KOH hydrolysis?

  • (i) and (ii) 

  • (iv)

  • (iii) and (iv)

  • (iii) and (iv)

  • (iii) and (iv)

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179.

A magnetic moment of 1.73 BM will be shown by one among the following

  • [Cu(NH3)4]2+

  • [Ni(CN)4]2-

  • TiCl4

  • TiCl4

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180.

Which of the following paramagnetic?

  • CO

  • O2-

  • CN-

  • CN-

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