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ENC702S - ENVIRONMENTAL CHEMISTRY - 2ND OPP - JANUARY 2025 |
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nAmlBIA UnlVERSITY
OF SCIEnCEAnDTECHnOLOGY
Facultyof Health,Natural
ResourcaensdApplied
Sciences
Schoolof NaturalandApplied
Sciences
Departmentof Biology,
ChemistryandPhysics
13Jac\\'.sonK3ujcuaStreet
Private aas1-33!!9
Windhoek
NAMIBIA
T: +2E4612072012
F: +2e4612079012
E: d~cp@nusr.na
W: www.nust.na
QUALIFICATION : BACHELOR OFSCIENCE
QUALIFICATION CODE: 07BOSC
LEVEL: 7
COURSE: ENVIRONMENTAL CHEMISTRY
DATE: JANUARY 2025
DURATION: 3 HOURS
COURSECODE: ENC702S
SESSION: 1
MARKS: 100
SUPLEMENTARY/SECOND OPPORTUNITY: EXAMINATION QUESTION PAPER
EXAMINER:
MODERATOR:
Mr Tjaronda Karumendu, Mr Festus Shafodino
Prof. James Abah
INSTRUCTIONS
1. Answer all questions on the separate answer sheet.
2. Please write neatly and legibly.
3. Do not use the left side margin of the exam paper. This must be allowed for the
examiner.
4. No books, notes and other additional aids are allowed.
s. Mark all answers clearly with their respective question numbers.
PERMISSIBLE MATERIALS
1. Non-Programmable Calculator
This paper consists of 3 pages including this front page and Periodic table.
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Question 1
[25]
1.1. The figure below illustrates how energy and matter are exchanged between the
different spheres.
Atmosphere
rfWj)
Biosphere
~eosph~drosphere
Using the Sulfur geochemical cycle, give one example showing the interaction between
each sphere.
{12)
1.2. Describe two major factors that may contribute to global environmental degradation.
(2)
1.3. Briefly explain what Green Chemistry is and how important it is for both industry and
our ecosystem.
{5)
1.4. What is the name given to elements that are distributed at higher concentrations in
localized areas when their extraction and refining are economically feasible and discuss
two general processes that result in these localized excesses.
{6)
Question 2
[25]
2.1. Explain ozone depletion and formation of ozone holes in the Antarctica regions. {10)
2.2. Describe how and where {tropic level) nitric oxide is responsible for the formation of
ozone. Show reactions and the sources of all reactants involved.
{4)
2.3. Which of the following compounds I or II, 1) is more likely to be transported further in
the atmosphere, 2) is more persistence in organism, and 3) is more toxic. Explain each
of your choices.
{6)
Cl
I Cl
Cl
II
Cl
Cl
Cl
Cl
2.4. What is air pollution and provide the four (4) bases on which air pollutants are classified
on.
{5)
Environmental Chemistry {ENC702S)
Supplementary/2 nd Opportunity January 2025 2
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Question 3
(23]
3.1. State two (2) of the reasons that account for the variations in the amount of dissolved
oxygen in water bodies.
(2}
3.2. Water is one of the scarcest commodities in many communities and this is often
exacerbated by the increasing rate of water pollution. State four (4) effects of
complexation in water?
(4)
3.3. Name three markers of water pollution and their corresponding sources of pollution. (3}
3.4. State four (4) chemical properties of acid mine drainage?
(4)
3.5. Define the term eutrophication and propose a way how it can be controlled.
(3}
3.6. What is BOD, and what does it stand for?
(3}
3.7. Describe ways in which measures taken to alleviate water supply and flooding problems
might actually aggravate such problems.
(4)
Question 4
(22]
4.1. Discuss the composition of the soil.
(5)
4.2. Discuss how the following factors can contribute to soil formation.
a. Climate
(2)
b. Living organisms
(2)
4.3. Soil continues to develop until layers called horizons form. With the aid of a well
labelled diagram, discuss the several types of soil horizons.
(8)
4.4. Many fish are found floating dead in a lake rich in phytoplankton, despite no evidence
of toxic dumping. State the phenomenon being implied and suggest three possible
reasons for the fish kill.
(5)
Question 5
[S]
In a small agricultural town, crops have been mysteriously failing for the past few seasons.
The leaves are turning yellow, and the yields are significantly lower than in previous years.
Local farmers have noticed an unusual, oily residue on the surface of their soil, which seems
to be spreading across the fields. Tests reveal that the soil has high levels of heavy metals,
particularly lead and cadmium, likely due to runoff from a nearby industrial site. The pollution
has not only affected the crops but also seeped into the groundwater, posing a threat to the
health of the community.
Based on the given scenario, what measures would you propose to mitigate contamination
of soil and/or groundwater by heavy metals?
(5)
***** END OF QUESTION PAPER*****
Environmental Chemistry (ENC702S}
Supplementary/2 nd Opportunity January 2025 3