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Heh 107 Question Paper

Heh 107

Course:Bachelor Of Science In Environmental Health

Institution: Kenyatta University question papers

Exam Year:2012

KENYATTA UNIVERSITY
UNIVERSITY EXAMINATIONS 2011/2012
INSTITUTIONAL BASED PROGRAMME (DECEMBER SESSION)
EXAMINATION FOR THE DEGREE OF BACHELOR OF SCIENCE
(ENVIRONMENTAL HEALTH)
HEH 107:
ENVIRONMENTAL CHEMISTRY I
===============================================================
DATE: WEDNESDAY 2ND MAY 2012
TIME: 4.30 P.M. – 6.30 P.M.

INSTRUCTIONS
1.
Section A is Compulsory
2.
Answer question 2 in Section B and TWO other Questions
3.
Electronic calculators may be used.

Known facts / Vital information

Speed of light, C = 2.998 x 108 m/s
Planck’s constant, h = 6.6262 x 10 -34 Js
Rydbergs constant, R = 109677.8 cm -1
1nm = 10-9 m

SECTION A (20 MARKS)

1.
Define the following terms
a)
Eutrophication
b)
Greenhouse effect
c)
Orbital
d)
Oxygen hole

(4 marks)

2.
a)
Write the electron configuration of the following elements.

X (16)

Z (27)

(2 marks)

Page 1 of 3

b)
The following rules are helpful in filing in electrons into orbitals. State them

(2 marks)

i)
Hunds rule

ii)
Paul’s Exclusion principle

3.
Distinguish between the following terms

i)
Soap and Detergent

(4 marks)

ii)
In chain polymerization and in step-growth polymerization

4.
Give relevant examples to 3 (i) and 3(ii) above.

(4 marks)

5.
State any 2 assumptions of the Neil Bohr atomic model.

(2 marks)

6.
Using hybridization, outline how a PVC is formed.

(2 marks)

SECTION B
Question 2
a)
An experiment was conducted by Peter, a member of your class. He passed light
(x-484nm) through a N2O filled glass tube. He noted that the light that came out of
the glass had increased by 60 nm.
i)
Discuss the rationale behind this change and calculate the energy change
associated with this observation.

(12 marks)

b)
Give the products of decomposition of carbon, sulphur, phosphorous and nitrogen in
wastewater under different oxygen concentrations.

(8 marks)

Question 3
a)
Discuss the theories of Acid-rain formation.

(9 marks)
b)
With relevant examples give three effects of acid rain to our ecosystem. (6 marks)

Page 2 of 3

Question 4
a)
Describe how photochemical smog is formed.

(5 marks)
b)
Critique the following suggestions on ozone depletion.

i)
Chapman’s mechanism

ii)
Rowland and Molina’s suggestions.

(10 marks)

Question 5
Describe each of the following cycles, giving critical attention to important chemical
processes.
i)
Nitrogen cycle
ii)
Carbon cycle
iii)
Water cycle

(15 marks)

Heh 107 Question Paper

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