Past paper

Form 4 Chemistry national exam 2024 with answers

The 2024 Form 4 national exam paper for Form 4 Chemistry, question by question. Take it timed like the real exam, then see the answer and explanation to every question.

70 questions, 100 marks
120 minutes

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120 minutes, 100 marks. Multiple choice is marked for you; you mark your written answers against the marking points.

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Instructions to candidates

Answer all questions in the ANSWER BOOKLET.

SECTION A: MULTIPLE CHOICE: CIRCLE THE LETTER OF THE CORRECT ANSWER [20 MARKS]

1
All group IA elements are found in block:
- A.S- block
- B.P- block
- C.D- block
- D.F- block
1 mark
2
The figure below states a change of state of matter. What change state of matter occur at B? (Figure: solid --melting--> liquid --A--> gas; gas --C--> liquid; liquid --B--> solid.)
1 mark
3
The correct sequence of the electron configuration of S16 atom is:
- A.1S^2 2S^2 2P^6 3S^2 3P^6
- B.1S^2 2S^2 2P^6 3S^2 3P^4
- C.1S^2 2S^2 2P^6 3S^2 3P^3
- D.1S^2 2S^2 2P^6 3S^2 3P^5
1 mark
4
Which of the following is the main component of natural gas?
- A.Methane
- B.Ethane
- C.Propane
- D.Butane
1 mark
5
The isotope of 26/12 Mg, the number of protons and neutrons in the nucleus of magnesium atom respectively is:
- A.14 and 12
- B.16 and 12
- C.12 and 26
- D.12 and 14
1 mark
6
By applying the formula 2^(n-4)+3, how many possible isomers of nonane (C9H20) can have?
- A.32
- B.35
- C.34
- D.33
1 mark
7
The decomposition of N2O5 is described by the following reaction 2 N2O5(g) → 4NO2(g) + O2(g). If O2 is being formed at rate of 4.8mol/min, what is the rate at which N2O5 is used up?
- A.2.4mol/min
- B.4.8 mol/min
- C.9.8 mol/min
- D.9.6 mol/min
1 mark
8
The IUPAC name for the structure below is: CH3-CH(CH3)-CH(Cl)-CH2-CH(OH)-CH2-CH3 (a CH3 branch on carbon 2, Cl on carbon 3, OH on the fifth carbon, the last CH2 carrying a CH3).
- A.5-chloro-1,6-dimethyl-3-heptanol
- B.1,6-dimethyl-5-chloro-3-hexanol
- C.3-chloro-2-methyl-5-heptanol
- D.5-chloro-6-methyl-3-heptanol
1 mark
9
If R= k[A]^2[B], the overall order reaction is:
- A.1
- B.2
- C.3
- D.4
1 mark
10
Which of the following changes indicates reduction reaction?
- A.Cu becomes Cu^+2
- B.Sn^+2 becomes Sn^+4
- C.Ag becomes Ag^+
- D.Fe^+3 becomes fe^+2
1 mark
11
In the figure below, which of this has the least penetrating power?
- A.Alpha
- B.Beta
- C.Gamma
- D.Neutron
1 mark
12
Which one of the following is NOT conditions necessary for the reaction to attain equilibrium? The reaction must be:
- A.in closed system
- B.reversible reaction
- C.in an open system
- D.at constant temperature
1 mark
13
in the reaction of Glucose and fructose produces:
- A.Lactose
- B.Sucrose
- C.Cellulose
- D.Amylose
1 mark
14
Ethanol is a member of homologous series of
- A.Alkane
- B.Alkyne
- C.Aromatics
- D.Alcohol
1 mark
15
A solution with PH of 8.5 is
- A.Basic
- B.Acidic
- C.Neutral
- D.Salt
1 mark
16
The functional group of Aldehyde is
- A.-CO-
- B.-OH
- C.-COOH
- D.-CHO
1 mark
17
Which of the following p-block elements is also called chalcogen
- A.Boron family
- B.Oxygen family
- C.Nitrogen family
- D.Carbon family
1 mark
18
The reaction between alcohol and carboxylic acid in the presence of acid catalyst forms:
- A.Ester
- B.Ether
- C.Amide
- D.Aldehyde
1 mark
19
The relative atomic mass(RAM) of Na2SO4 [Na=23, S=32 O=16] is
- A.114g/mol
- B.124g/mol
- C.142g/mol
- D.144g/mol
1 mark
20
For the reaction: 2SO2(g) + O2(g) → 2SO3(g); Which direction will the equilibrium shift, if the pressure of the system is decreased?
- A.No affect
- B.Same constant
- C.Right
- D.Left
1 mark

SECTION B: FILL IN THE BLANK SPACES (10 MARKS)

Use the words in the box to fill in the blank spaces: oxidation, mechanism, covalent, aqueous solution, atom, chemical kinetics, ether, thermodynamics, reversible, endothermic

B1
Use the words in the box: oxidation, mechanism, covalent, aqueous solution, atom, chemical kinetics, ether, thermodynamics, reversible, endothermic. _____ is defined as loss of electrons by an atom
1 mark
B2
Use the words in the box: oxidation, mechanism, covalent, aqueous solution, atom, chemical kinetics, ether, thermodynamics, reversible, endothermic. _____ is the smallest particle of an element that can take part in chemical reaction.
1 mark
B3
Use the words in the box: oxidation, mechanism, covalent, aqueous solution, atom, chemical kinetics, ether, thermodynamics, reversible, endothermic. _____ is the branch of physical chemistry that studies the heat flow.
1 mark
B4
Use the words in the box: oxidation, mechanism, covalent, aqueous solution, atom, chemical kinetics, ether, thermodynamics, reversible, endothermic. A reaction that can proceed both forward and backward reaction is called_____ reaction
1 mark
B5
Use the words in the box: oxidation, mechanism, covalent, aqueous solution, atom, chemical kinetics, ether, thermodynamics, reversible, endothermic. If we use water as a solvent, then the solution is called_____
1 mark
B6
Use the words in the box: oxidation, mechanism, covalent, aqueous solution, atom, chemical kinetics, ether, thermodynamics, reversible, endothermic. CH3-CH2-O-CH2-CH3 is an example of _____
1 mark
B7
Use the words in the box: oxidation, mechanism, covalent, aqueous solution, atom, chemical kinetics, ether, thermodynamics, reversible, endothermic. The reaction that absorbs energy is called _____ reaction
1 mark
B8
Use the words in the box: oxidation, mechanism, covalent, aqueous solution, atom, chemical kinetics, ether, thermodynamics, reversible, endothermic. _____ is a branch of chemistry that deals with rate of reaction, factors affecting these rates and mechanism of reaction
1 mark
B9
Use the words in the box: oxidation, mechanism, covalent, aqueous solution, atom, chemical kinetics, ether, thermodynamics, reversible, endothermic. The sequence of elementary steps that together make a complete chemical reaction is known as _____ of reaction.
1 mark
B10
Use the words in the box: oxidation, mechanism, covalent, aqueous solution, atom, chemical kinetics, ether, thermodynamics, reversible, endothermic. There are two major types of chemical bonding: ionic bond and _____ bond.
1 mark

SECTION C: MATCHING (10 MARKS)

Match the words in Column A with corresponding words in Column B using the Brackets

C1
Match the word in Column A with the corresponding words in Column B. Column A: Carbohydrates. Column B: the short chains attached to the parent chain; reaction between acids and bases to form salt; the most abundant isotope of hydrogen; the longest straight chain of carbon atom; formula of Kc; is the product of oxidation of aldehydes; reaction in which one atom is displaced by another atom; is the isomer of the formula of alkene; the most abundant organic compound in nature; formula of Kw.
1 mark
C2
Match the word in Column A with the corresponding words in Column B. Column A: [Product]/[Reactant]. Column B: the short chains attached to the parent chain; reaction between acids and bases to form salt; the most abundant isotope of hydrogen; the longest straight chain of carbon atom; formula of Kc; is the product of oxidation of aldehydes; reaction in which one atom is displaced by another atom; is the isomer of the formula of alkene; the most abundant organic compound in nature; formula of Kw.
1 mark
C3
Match the word in Column A with the corresponding words in Column B. Column A: Neutralization. Column B: the short chains attached to the parent chain; reaction between acids and bases to form salt; the most abundant isotope of hydrogen; the longest straight chain of carbon atom; formula of Kc; is the product of oxidation of aldehydes; reaction in which one atom is displaced by another atom; is the isomer of the formula of alkene; the most abundant organic compound in nature; formula of Kw.
1 mark
C4
Match the word in Column A with the corresponding words in Column B. Column A: Substitution. Column B: the short chains attached to the parent chain; reaction between acids and bases to form salt; the most abundant isotope of hydrogen; the longest straight chain of carbon atom; formula of Kc; is the product of oxidation of aldehydes; reaction in which one atom is displaced by another atom; is the isomer of the formula of alkene; the most abundant organic compound in nature; formula of Kw.
1 mark
C5
Match the word in Column A with the corresponding words in Column B. Column A: Parent chain. Column B: the short chains attached to the parent chain; reaction between acids and bases to form salt; the most abundant isotope of hydrogen; the longest straight chain of carbon atom; formula of Kc; is the product of oxidation of aldehydes; reaction in which one atom is displaced by another atom; is the isomer of the formula of alkene; the most abundant organic compound in nature; formula of Kw.
1 mark
C6
Match the word in Column A with the corresponding words in Column B. Column A: Cycloalkane. Column B: the short chains attached to the parent chain; reaction between acids and bases to form salt; the most abundant isotope of hydrogen; the longest straight chain of carbon atom; formula of Kc; is the product of oxidation of aldehydes; reaction in which one atom is displaced by another atom; is the isomer of the formula of alkene; the most abundant organic compound in nature; formula of Kw.
1 mark
C7
Match the word in Column A with the corresponding words in Column B. Column A: Side chain. Column B: the short chains attached to the parent chain; reaction between acids and bases to form salt; the most abundant isotope of hydrogen; the longest straight chain of carbon atom; formula of Kc; is the product of oxidation of aldehydes; reaction in which one atom is displaced by another atom; is the isomer of the formula of alkene; the most abundant organic compound in nature; formula of Kw.
1 mark
C8
Match the word in Column A with the corresponding words in Column B. Column A: [H3O][OH-]. Column B: the short chains attached to the parent chain; reaction between acids and bases to form salt; the most abundant isotope of hydrogen; the longest straight chain of carbon atom; formula of Kc; is the product of oxidation of aldehydes; reaction in which one atom is displaced by another atom; is the isomer of the formula of alkene; the most abundant organic compound in nature; formula of Kw.
1 mark
C9
Match the word in Column A with the corresponding words in Column B. Column A: Carboxylic acid. Column B: the short chains attached to the parent chain; reaction between acids and bases to form salt; the most abundant isotope of hydrogen; the longest straight chain of carbon atom; formula of Kc; is the product of oxidation of aldehydes; reaction in which one atom is displaced by another atom; is the isomer of the formula of alkene; the most abundant organic compound in nature; formula of Kw.
1 mark
C10
Match the word in Column A with the corresponding words in Column B. Column A: Protium. Column B: the short chains attached to the parent chain; reaction between acids and bases to form salt; the most abundant isotope of hydrogen; the longest straight chain of carbon atom; formula of Kc; is the product of oxidation of aldehydes; reaction in which one atom is displaced by another atom; is the isomer of the formula of alkene; the most abundant organic compound in nature; formula of Kw.
1 mark

SECTION D: STRUCTURED QUESTIONS (60 MARKS)

D1a
Define the following term: Alkene (2 marks)
2 marks
D1b
Define the following term: Ether (2 marks)
2 marks
D1c
Define the following term: Nuclear chemistry (2 marks)
2 marks
D2a
If the concentration of HNO3 in a solution is 0.025M, Calculate: pH (2 marks)
2 marks
D2b
If the concentration of HNO3 in a solution is 0.025M: Name HNO3 (2 marks)
2 marks
D2c
If the concentration of HNO3 in a solution is 0.025M: Determine its conjugate bases (1 marks)
1 mark
D3a
Differentiate between Primary alcohol and secondary alcohol (2 marks)
2 marks
D3b
Differentiate between Nuclear fusion and nuclear fission (2 marks)
2 marks
D3c
Differentiate between Ketone and aldehyde (2 marks)
2 marks
D4a
Draw the structural formula of: 2,4,5-trimethyloctane (2 marks)
2 marks
D4b
Draw the structural formula of: 4-chloro-2-pentanol (2 marks)
2 marks
D4c
Draw the structural formula of: 2-methoxypropane (2 marks)
2 marks
D5a
Cesium-137, used in cancer treatment, has a half-life of 30 yrs. Write the balanced nuclear equation for the beta decay of Cs-137 (137/55 Cs). (2 marks)
2 marks
D5b
Cesium-137, used in cancer treatment, has a half-life of 30 yrs. How many milligrams of a 16 mg sample of cesium-137 remain after 90 yrs. (3 marks)
3 marks
D6
Classify the following in to exothermic and endothermic reactions (4 marks): Photosynthesis, Combustion, Respiration, Cracking of alkanes
4 marks
D7a
Bromine has an atomic number of (Z=35) has a nuclear symbol of 80/35 Br. Write the electron configuration of Br35, using sub-shell notation (2 marks)
2 marks
D7b
Bromine has an atomic number of (Z=35) has a nuclear symbol of 80/35 Br. state the block which bromine belongs to? (2 marks)
2 marks
D7c
Bromine has an atomic number of (Z=35) has a nuclear symbol of 80/35 Br. Write the valence electron of bromine? (2 marks)
2 marks
D8a
Below is a Grid representing a part of periodic table (it shows Li and Na in the first column, Ca in the second column, Al, Cl and Ar on the right). Which two elements are in the same group? (2marks)
2 marks
D8b
Below is a Grid representing a part of periodic table (it shows Li and Na in the first column, Ca in the second column, Al, Cl and Ar on the right). Which element belongs to boron family? (1mark)
1 mark
D8c
Below is a Grid representing a part of periodic table (it shows Li and Na in the first column, Ca in the second column, Al, Cl and Ar on the right). Which elements belongs to p-block elements (3 marks)
3 marks
D8d
Below is a Grid representing a part of periodic table (it shows Li and Na in the first column, Ca in the second column, Al, Cl and Ar on the right). What name is given to the elements in group eight or Zero? (1 marks)
1 mark
D8e
Below is a Grid representing a part of periodic table (it shows Li and Na in the first column, Ca in the second column, Al, Cl and Ar on the right). Write the full names for the symbols: i) Na ii. Ar (2marks)
2 marks
D9a
Answer the following questions related to the chemical equilibrium concept: What are types of chemical equilibrium? (2 Marks)
2 marks
D9b
Calculate the Kc from the following equilibrium concentrations for the reaction 3H2(g) + N2(g) → 2NH3(g): [H2] = 0.0163 M, [NH3] = 0.0165 M, [N2] = 0.65 M (4 Marks)
4 marks
D9c
For the reaction 3H2(g) + N2(g) → 2NH3(g) with Kc of about 97: Does this reaction is product favored or reactant favored? (1marks)
1 mark
D10a
238/92 U → 4/2 He + A/Z X + 2 0/0 γ. What are types of radioactive decays? (3 marks)
3 marks
D10b
238/92 U → 4/2 He + A/Z X + 2 0/0 γ. Which kind of radioactive decays occurs in the equation above? (1 marks)
1 mark
D10c
238/92 U → 4/2 He + A/Z X + 2 0/0 γ. Identify the value of A (1 marks)
1 mark
D10d
238/92 U → 4/2 He + A/Z X + 2 0/0 γ. Identify the value of Z (1 marks)
1 mark

Paper set by the Federal Ministry of Education, Culture and Higher Education (MoECHE), Somalia. Shared free of charge to help students prepare. The answers and explanations are written by Sheerxirfad teachers.

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