NATIONAL OPEN UNIVERSITY OF NIGERIA

UNIVERSITY VILLAGE, PLOT 91, CASDASTRAL ZONE, NNAMDI AZIKIWE EXPRESS WAY, JABI, ABUJA.
FACULTY OF SCIENCES
APRIL/MAY 2019 EXAMINATION

COURSE CODE:        CHM 406

COURSE TITLE:         Nuclear and radiochemistry

COURSE UNIT:          2

TIME:                          2 Hours

INSTRUCTION:          Answer question one and any three questions.

QUESTION ONE

1ai. Are the nuclei above the stability belt neutron rich or neutron poor?                                            1 mark

1aii. Explain how the nuclei with high ratio of neutron to protons than those within the stability belt can attain stability.                                                                                                                                                   6 marks

1b. Identify the symbol  X in each of the following:

i)            ⁰_-1X = ? ^(1/2)    2 mks          (ii)  ⁴₂ X = ? ^(1/2)    2mks     (iii)  ⁰₊₁ X = ?^(1/2)     2 mks  (iv)                 ¹₀ X = ?^(1/2)                                    2 mks    

1c. . In energetic of nuclear radiation study, list the objectives a facilitator intends to achieve.      3 marks

1d. Explain (i) Thermal neutrons (ii) Moduration                                                                                        3 marks

1e. In large organization, discuss the three stages involved in protection of radiation.                      4 marks

QUESTION TWO

2a. Define radioactive decay.                                                                                                                          2 marks

2b. Enumerate the properties of particles emitted by radioactive decay.                                             9 marks

2c. Differentiate K-capture from L-capture.                                                                                                2 marks

2d. Complete and balance the following equations:

i) ¹⁴₇N + ¹_?n → ^?₆C + ¹₁H                                                                                                                                   1 mark

ii) ¹⁴₆C → ¹⁴₇N + ?                                                                                                                                             1 mark

QUESTION THREE

3a. Explain briefly the following:

1. Chain reaction                                                                                                                            2 mark
2. Nuclear Fission                                                                                                                           2 mark
3. Nuclear Fusion                                                                                                                           2 mark
4. Nuclear Fusion Reactor                                                                                                             3 mark

3b. Complete and balance the equations below:

i) ¹₀n → ¹₁P + ?                                                                                                                                  2 mark

ii)  ?  → ⁴⁰₂₀Ca + ⁰_-1β                                                                                                             2 mark

iii) ⁴He₂ + ¹⁴N₁ → ¹H₁ + ?                                                                                                                2 mark

QUESTION FOUR

4a. With specific examples explain the application of radiation in

1. Agriculture  2 mks (i Industry  3 mks (ii Medical uses  3 mks (iv) Scientific research  2 mks (v) Archeology      1 mk

4bi.Under what condition do you say that the nucleus of an atom is dense?  

                                                                                                                                                                             2 marks

4b ii)      ⁹⁷₄₀Zr → ⁹⁷₄₁Nb + ?                                                                                                                              2 marks

QUESTION FIVE

5a. Identify and discuss the radioactive process in the chemical equation below

92238U                        90234Th   +  24He                                                                                                              5 marks

5b. Mention any three rules that guide prediction of nuclear stability.                                                 3 marks

5c. Explain decay process in terms of energy loss.                                                                                     3 marks

5d.Complete the following nuclear reactions using the symbol X to represent the new element formed or particle involved.

1. 1938 K                             X  +   +10β                                                                                                      2  marks

2. 47106 Ar     +    X                                  46106 Pd                                                                                     2 marks