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National Open University Exam Past Question – CHM 303 OCTOBER/NOVEMBER 2014 EXAMINATION

NATIONAL OPEN UNIVERSITY OF NIGERIA

1416 AHMADU BELLO WAY, VICTORIA ISLAND LAGOS SCHOOL OF SCIENCE AND TECHNOLOGY

OCTOBER/NOVEMBER 214 EXAMINATION

 

CHM 303 – INORGANIC CHEMISTRY III Instruction-   Answer any five questions Time-2½Hours

 

1ai. Briefly explain why XeF4 has square planar structure.2mks

 

  1. Juxtapose why vander waals force between the noble gas atoms increase down the group. 3mks

 

  1. b Write short notes on the following;

 

  1. Lambda point. 2mks
  2. Super conductivity. 2mks iii.       Radon. 2mk

 

  1. c. Using chemical equations show the formation of Xenon Tetra fluoride.3mks

 

2ai. Write balanced chemical equations to describe the reaction of potassium metal with:

 

(i) oxygen     (ii) water     (iii) chlorine  (6 marks)

 

  1. b. Work out the oxidation states of xenon in XeF4 and XeF6 (2mks)

 

  1. c. Given below in Column I are the few expected compounds of noble gases. Write down in Column II the shapes of these compounds on the basis of VSEPR th (3mks)

 

Column I                                        Column

 

(i)   XeOF4                                           (ii)                                                

 

 

(ii)   XeO4                                             (iii)                                                 

 

 

(iii)   XeF6                                             (iii)                                                   

 

  1. d. State three State four uses of hydrogen. (3mks)

 

Question Three

 

3a. (i) List and describe the isotopes of hydrogen (3 marks)

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(ii) What do you understand by the term ‘active hydrogen’? (2 marks)

 

  1. b. Discuss the classification of ligands in coordination chemistry (6 marks) Question Four

4ai. What are β rays? (2 marks)

 

 

  1. b. Discuss briefly the principles of the valence bond theory (6 marks)

 

 

  1. c. Highlight the differences between the valence bond and molecular orbital theories (6marks)

 

Question Five

 

 

5a (i) What is the difference between gangue and slag? (4 mks)

 

(ii) Write balanced chemical equations to show how the flux forms the slag in an iron blast furnace. (4 mks)

 

(b) (i) Why is it necessary to concentrate the ores before extracting metals from them?( 2 mks)

 

(ii)  Describe  the  froth  flotation  process  for  the  concentration  of  ores. (4mks)

 

Question Six

 

6ai. List and give the electronic configurations of the 3d transition elements (8 mks)

 

(b) What are rare earth elements? Why are they so called? (2 mks)

 

(c) (i) Identify the most common oxidation state for the lanthanides and the actinides (2 mks)

 

(ii) How is this oxidation state formed? (2 mks) Question Seven

7ai. How do the following properties vary in the transition elements? (6 marks) (i)       Atomic size

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(ii)         Ionisation energy

 

(iii)        Electronegativity

 

(b) Highlight four characteristics of transition metals (4 mks)

 

(c) (i) Explain briefly why CuSO4 is blue while ZnSO4 is white (2 marks) (ii) Predict the spin-only magnetic moment for: (2 marks)

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