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ENC702S - ENVIRONMENTAL CHEMISTRY - 1ST OPP - NOVEMBER 2023 |
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nAmlBIA UnlVERSITY
OF SCIEnCEAnDTECHnOLOGY
Facultyof Health,Natural
ResourceasndApplied
Sciences
Schoool f NaturalandApplied
Sciences
Departmentof Biology,
Chemistryand Physics
QUALIFICATION: BACHELORof SCIENCE
QUALIFICATIONCODE: 07BOSC
COURSE:ENVIRONMENTAL CHEMISTRY
DATE: NOVEMBER 2023
DURATION: 3 HOURS
13JacksonKaujeua Street
Private Bag 13388
Windhoek
NAMIBIA
T: +264612072012
F: •264 612079012
E: dbcp@nust.na
W: www.nust.na
LEVEL:7
COURSECODE: ENC702S
SESSION: 1
MARKS: 100
FIRST OPPORTUNITY: QUESTION PAPER
EXAMINER:
MODERATOR:
Dr. Mpingana N. Akawa
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.
5. Mark all answers clearly with their respective question numbers.
PERMISSIBLE MATERIALS
1. Non-Programmable Calculator
ATTACHEMENTS
This paper consists of 3 pages including this front page
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QUESTION 1
[201
a) The mechanism by which the earth self regulates its temperature is called the carbon
dioxide cycle. Starting with the carbon dioxide in the atmosphere, explain the CO2
cycle.
(10)
b) The atmosphere of the earth is slightly warmer that what it should be due to direct
solar heating because a mild case of greenhouse effect. Explain how greenhouse
affects the earth's atmosphere.
(10)
QUESTION 2
[201
a) With the aid of chemical reactions, explain how acid mine drainage (AMD) is formed.
(10)
b) Discussthe ecological impact of acid mine drainage.
(5)
c) Explain how AMO can be prevented.
(5)
QUESTION 3
[201
a) Explain how the hydrologic cycle contributes to groundwater pollution and discuss the
preventative measures of groundwater pollution.
(10)
b) Provide the likely source of the following water pollutants and discuss their effect on living
organisms?
(6)
i. Herbicides
ii. Fecal coliform bacteria
iii. Pharmaceutical metabolites
c) NO2 is a common air pollutant that undergoes photochemical reactions which results in
stratospheric destruction of ozone layer, formation of photochemical smog and acid rain.
Describe two ways in which NO2concentration in the atmosphere can be controlled. (4)
QUESTION 4
[201
a) Air pollutants may be classified based on the differences in their physical or chemical
characteristics. Describe (with an example for each case) the different classes of
pollutants that fall within this category.
(8)
b) Briefly describe the Goldschmidt's geochemical classifications of elements.
(8)
Environmental Chemistry (ENC702S)
1st Opportunity November 2023 2
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c) Provide the major categories of concern regarding pesticides and their residues in soil.
(4)
QUESTION 5
[20)
a) Briefly define water eutrophication and explain why it is considered as a case of
pollution.
(8)
b) What is a water table?
(2)
c) How important is the water table with respect to pollution impact monitoring? (2)
d) Complexation reactions involving chelating agents and metal ions are among the
reactions which occur in the aquatic environment.
i)
What are chelating agents?
(2)
ii)
Why are chelating agents considered as water pollutants of concern?
(6)
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END OF QUESTION PAPER
Environmental Chemistry (ENC702S)
1st Opportunity November 2023 3