TTC NATIONAL EXAMINATIONS, 2023-2024 PDF Free Download
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2023-2024-NESA (National Examination and School Inspection Authority) CHE 01 Page 1 of 8
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TTC NATIONAL EXAMINATIONS, 2023-2024
OPTION: SCIENCE AND MATHEMATICS EDUCATION (SME)
SUBJECT: CHEMISTRY
DURATION: 3 HOURS
Instructions to candidates:
1) Write your names and index number on the answer booklet as written on your
registration form and DO NOT write your names and index number on additional
answer sheets if provided.
2) DO NOT open this question paper until you are told to do so.
3) This paper consists of THREE sections: A, B and C.
- Section A: Attempt ALL questions. (55 marks)
- Section B: Attempt any THREE questions. (30 marks)
- Section C: Attempt any ONE question. (15 marks)
4) You do not need the Periodic Table.
5) Silent-non programmable calculators may be used.
6) Use only a blue or black pen for answering and a pencil for drawing.
Chemistry
CHE 01
26/07/2024 08:30 AM – 11:30 AM
NATIONAL EXAMINATION AND
SCHOOL INSPECTION
AUTHORITY
2023-2024-NESA (National Examination and School Inspection Authority) CHE 01 Page 2 of 8
Section A: Attempt all questions (55 marks)
1) Choose the correct answer among the alternatives given.
a) The spin quantum number “ms” describes the: (1 mark)
i) spacial orientation of an orbital
ii) spin properties of an electron
iii) shape of an orbital
iv) energy of an orbital.
b) From the Bohr’s model, in hydrogen atom, the following series is found in visible
light. (1 mark)
i) Lymann iii) Pfund
ii) Brackett iv) Balmer
c) When performing the electron configuration of atoms and ions, the “Pauli
exclusion principle” says that: (1 mark)
i) no two electrons in an atom can have the same set of four quantum numbers
n, ℓ, mℓ and ms”.
ii) two electrons in an atom can have the same set of four quantum numbers n,
ℓ, mℓ and ms”.
iii) two electrons in two atoms can have the same set of four quantum numbers
n, ℓ, mℓ and ms”.
iv) no two electrons of two atoms can have the same set of four quantum
numbers n, ℓ, mℓ and ms”.
2) State whether each of the following statements is True or False.
a) Ionic bond involves transfer of electrons whereas covalent bond involves share of
electrons. (1 mark)
b) Malleability and ductility are physical properties of ionic compounds due to
positive and negative ions strongly held together.
(1 mark)
c) The solubility of ionic compounds is good only in non-polar solvents. (1 mark)
3) Choose the correct answer among the alternatives given.
a) The general formula for homologous series of alkynes is: (1 mark)
i) CnH2n+1 iii) CnH2n
ii) CnH2n+2 iv) CnH2n-2
b) Which of the following alkenes exhibits a cis-trans isomerism? (1 mark)
c) The reaction, is a radicalar addition
reaction and it follows the: (1 mark)
i) Zaitsev’s rule iii) Markovnikov’s rule
ii) Anti-Markovnikov’s rule iv) Huckel’s rule.
4) State whether each of the following statements is True or False.
a) All amines have acidic properties in nature. (1 mark)
b) Amino acids are organic compounds that contain both the amine group and acid
chloride group. (1 mark)
c) Dimethylamine is a stronger base than ethylamine. (1 mark)
i) CH2=CH2
iii) CH3-CH=CH-CH3
ii) CH3-CH=CH2
iv) CH3-CH=C(CH3)-CH3
CH3-CH=CH2 + HBr CH3-CH2-CH2Br
ROOR
2023-2024-NESA (National Examination and School Inspection Authority) CHE 01 Page 3 of 8
5) Match each concept on the left with its corresponding definition on the right.
The answers should be like: letter
¾®
number. (4 marks)
Concept
Definition
a) Enthalpy change of
hydration (ΔHhyd)
b) Enthalpy change of
solution (ΔHsln)
c) Open system
d) Closed system
i) is the enthalpy change when one mole of
aqueous ions is formed from gaseous ions.
ii) is a system that can exchange both matter
and energy with the surroundings.
iii) is a system that can exchange energy but
not matter with the surroundings.
iv) is the enthalpy change when one mole of an
ionic substance dissolves in enough solvent
to form an infinitely dilute solution.
6) Fill in the blank spaces with the appropriate terms provided.
aromatic compounds, acylation reaction, hydrocarbons, alkylation reaction.
a) Benzene and its derivatives are referred to as…………………….. (1 mark)
b) The substitution of a hydrogen atom with an alkyl group, -R, on benzene ring is
called……………………………... (1 mark)
c) …………………………. consists of substituting a hydrogen atom with an acyl
group, RCO-, on a benzene ring. (1 mark)
d) The same as other…………………….., benzene burns in plenty supply of air to
form carbon dioxide and water. (1 mark)
7) Choose the correct answer among the alternatives given.
a) The study of the rate of chemical reactions is called: (1 mark)
i) reaction rate iii) reaction speed
ii) reaction kinetics iv) reaction power
b) The homogeneous catalysis is said when: (1 mark)
i) the reactants are in aqueous state and catalyst is in solid state.
ii) the reactants are in gaseous state and catalyst is in the solid state.
iii) the reactants and catalyst are in the same physical state.
iv) the reactants and catalyst are in different physical states.
c) As the temperature of a reaction is increased, the rate of the reaction increases
because, (1 mark)
i) activation energy is lowered to a good speed.
ii) reactant molecules collide less frequently at low speed.
iii) reactant molecules collide less frequently and with more energy.
iv) reactant molecules collide more frequently and with more energy.
d) What action will lower the activation energy of a reaction? (1 mark)
i) Adding a catalyst on the reaction.
ii) Increasing the concentrations of reactants.
iii) Lowering the temperature of the reaction.
iv) Removing products as the reaction proceeds.
2023-2024-NESA (National Examination and School Inspection Authority) CHE 01 Page 4 of 8
8) The Table 1 below shows some Group 15 hydrides and their boiling points.
Hydride
Molecular weight
Boiling point/0C
Ammonia, NH3
17
-33
Phosphine, PH3
34
-88
Arsine, AsH3
78
-55
Stibine, SbH3
125
-17
Table 1
a) Arrange the above hydrides by their:
(i) increasing molecular weights. (1 mark)
(ii) increasing boiling points. (1 mark)
b) Explain the abnormal behaviour of ammonia in the trend of boiling points
compared to the trend of molecular weights. (2 marks)
(Electronegativity: N=3.0, P=2.1, As=2.1, Sb =2.0, H=2.1)
9) The ozonolysis of the alkene H can be done as shown here below.
a) Give the IUPAC name for the alkene H. (1 mark)
b) Identify the structures of P and Q. (2 marks)
c) Explain the need of using zinc in ethanoic acid in the hydrolysis step. (1 mark)
10) Esters can undergo different reactions including the following one.
a) Name the reaction above. (1 mark)
b) Give the chemical formulae of X and Y. (2 marks)
c) Write an equation for the complete combustion of C17H35COOCH3. (1 mark)
!
11) Consider the reversible reaction:
a) Write the expressions for both Kc and Kp for this reaction. (2 marks)
b) State and explain how you would expect the following changes to affect the
position of equilibrium:
(i) Increasing the pressure. (1 mark)
(ii) Adding a catalyst. (1 mark)
12) The radiocesium, , undergoes beta emissions with a half-life of 30 years.
a) Define the term half-life for a radioactive substance. (1 mark)
b) Write a balanced nuclear equation where emits beta particles ( 𝑒
!"
#) to
produce an element with chemical symbol, Ba. (1 mark)
+
CHOOCC17H31
CH2OOCC17H35
CH2OOCC17H29
+XC17H31COOH
C17H35COOH
C17H29COOH
Y
H+
heat
+
+
2A(g) + X(g) 4Q(g) +Z(g) DH < 0
55
137Cs
55
137Cs
2023-2024-NESA (National Examination and School Inspection Authority) CHE 01 Page 5 of 8
c) What fraction of Cs-137 remains in a sample of the isotope after 120 years?
(3 marks)
13) The pH of a 0.10M solution of a weak acid, carbonic acid, H2CO3, is 3.68.
a) Write the equation of ionization of the first proton from carbonic acid. (1 mark)
b) Find the concentration in hydrogen ions, [H+]. (1 mark)
c) Calculate the Ka of carbonic acid. (2 marks)
14) In industry, phenylethene (styrene) is made from benzene in a two-step process
as follows.
a) Suggest the reagent and conditions involved in step 1. (2 marks)
b) Give one major use of phenylethene (styrene). (1 mark)
c) Draw the mechanism to show how the product in step 1 is formed. (2 marks)
Section B: Attempt any three (3) questions (30 marks)
15) At 298K the solubility product (Ksp) of lead (II) chloride, PbCl2, is 1.6 x 10-5.
a) Explain what is meant by solubility product. (1 mark)
b) Write an equation of partial dissociation of PbCl2. (2 marks)
c) Express the Ksp for PbCl2. (2 marks)
d) The appropriate unit of Ksp for PbCl2 is: (1 mark)
A. mol2 dm-9 C. mol3 dm-9
B. mol9 dm-9 D. mol3 dm-6
e) Calculate the solubility of PbCl2 in water at 298K. (4 marks)
16) Chlorine as well as other halogens form several compounds in which they show
different oxidations states.
a) Write down the formulae of chlorine compound or ion in which chlorine shows
its:
(i) lowest oxidation state. (1 mark)
(ii) highest oxidation state. (1 mark)
b) The Table 2 below shows the boiling points of hydrogen halides.
Table 2
(i) Explain the trend in the boiling points of the hydrogen halides from HCl to
HI. (2 marks)
(ii) HF with the smallest molecular mass, has the highest boiling point of all
other hydrogen halides. Suggest a reason for this observation. (2 marks)
(iii) Explain the trend in acidic strength of the hydrogen halides from HCl to
HI. (2 marks)
2023-2024-NESA (National Examination and School Inspection Authority) CHE 01 Page 6 of 8
c) Identify a hydrogen halide which is:
(i) the most volatile. (1 mark)
(ii) is the strongest reducing agent. (1 mark)
17) Consider the following pairs of compounds, C-D and E-F
a) Define the term isomers. (1 mark)
b) State the type of isomers encountered in pairs of compounds:
(i) C-D (1 mark)
(ii) E-F (1 mark)
c) Give the IUPAC names for compounds C and F. (2 marks)
d) Identify the functional group found in:
(i) compound E. (1 mark)
(ii) compound F. (1 mark)
e) Indicate the reagent and condition that could be used to distinguish between
the compounds E and F. In each case state the expected observable changes.
(3 marks)
18) Given two complex compounds of cobalt: A = [Co(NH3)5SO4]Br and
B = [Co(NH3)5Br]SO4.
(Atomic numbers: Mn =25, Fe =26, Co = 27, Zn =30)
a) What ions will the complex A yield in solution? (2 marks)
b) Give the systematic IUPAC name of the complex B. (1 mark)
c) Write the electron configuration, in terms of s, p, d notation, of cobalt in the
complex B. (1 mark)
d) Zinc (Zn) and iron (Fe) are both d-block elements but iron can be magnetized
while zinc cannot. Explain this statement with support of electron
configurations. (3 marks)
e) Manganese form various ions including Mn2+ and Mn3+. Which of Mn2+ or Mn3+
is more stable? Justify your reasoning. (3 marks)
H3CCCH2-CH2-CH3
C
O
H3C-CH2-C-CH2-CH3
O
D
HC
OCH2-CH2-CH3
O
E
C
CH2-CH2-CH3
O
HO
F
2023-2024-NESA (National Examination and School Inspection Authority) CHE 01 Page 7 of 8
19) The diagram below shows an electrochemical cell designed to measure the
standard electrode potential for zinc.
a) Name the structure A and component B. (2 marks)
b) Explain the role of component B in this cell. (1 mark)
c) Predict the names of solutions C and E. (2 marks)
d) What is represented by the part D? (1 mark)
e) Name the substance F with its necessary conditions. (2 marks)
f) For the part D, copper rod (Cu) was used. Criticize this option by showing why
it is not suitable in that place. (2 marks)
Section C: Attempt any one (1) question (15 marks)
20) This question concerns the chlorides of some elements of the Period 3 of the
Periodic Table from sodium to sulphur. The melting points of these chlorides are
given here below.
*sublimes at 451K
a) Copy and complete the row of bonding using the terms ionic, ionic with covalence
and covalent. (3 marks)
b) Give the equation, with state symbols, for the reaction of phosphorus with
chlorine to form phosphorus (V) chloride, PCl5. (2 marks)
c) Explain why the melting point of MgCl2 is lower than the melting point of NaCl.
(2 marks)
d) The chlorides of sodium and aluminium dissolve in water according to the
following equations.
NaCl(s) + H2O(l) Na+(aq) + Cl+(aq)
AlCl3(s) + 6H2O(l) Al(H2O)6(aq)
3+ + 3Cl-(aq)
Al(H2O)6 + H2O(l)
3+
(aq) Al(H2O)5OH (aq)
2+ + H3O+(aq)
2023-2024-NESA (National Examination and School Inspection Authority) CHE 01 Page 8 of 8
(i) Choose the correct answer and justify your reasoning. The solution of sodium
chloride has a pH which: (2 marks)
a) is less than 7 c) is greater than 7
b) is equal to 7 d) is equal to 10.
(ii) Choose a correct answer and justify your reasoning. The solution of
aluminium chloride is: (2 marks)
a) amphoteric c) neutral
b) basic (alkaline) d) acidic.
e) Phosphorus (P) combines with oxygen (O2), to form phosphorus (V) oxide which
is reacted with water to produce phosphoric acid, H3PO4(aq). Starting from
phosphorus and oxygen, with all state symbols on substances, write the two (2)
balanced equations to show how phosphoric acid is obtained. (4 marks)
21) Consider the following three reactions of cyclohexanone, C6H10O.
(Atomic masses: H =1, C = 12, O =16)
a) Write the structural formula of the compound X from reaction 1. (1 mark)
b) Give the reagent Y from the reaction 2. (1 mark)
c) Outline the mechanism for the reaction 2. (3 marks)
d) State the type of reaction 2. (1 mark)
e) Calculate the theoretical mass of the product formed in reaction 3 given that
2.40 g of cyclohexanone were allowed to react. (3 marks)
f) In one or more steps show how the following conversions can be performed. (Use
the mineral reagents only and show the reaction conditions where necessary).
(i) From H2C=CH2 to CH3-CHO (3 marks)
(ii) From CH3-CH2-CH2Br to CH3-CO-CH3 (3 marks)
-END-
