Grade 9
29,02,2024
Semester Test
Subject: Chemistry
120mi
ns
/100
General Instructions:
(i) Answer all questions.
(ii) Read each question carefully before providing an answer.
(iii) Section A comprises 25 True and false questions, totaling 25 marks. Section B consists of 20 Multiplechoice questions, each worth 1 mark. Section C comprises of 3 Structural questions each worth 5 marks.
Section D includes 17 Direct questions each worth 2 marks, except last two 5 marks each totaling 40 marks.
Section A: True or false questions: (25 questions – 25 Marks)
1. The number of neutrons may be different in the atoms of the same element. [
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2. Atoms of the same element with different numbers of neutrons called isotopes of that element. [
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3. The atomic mass in the periodic table is the average mass of the different isotopes of an element. [
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4. The number of electrons in an atom of an element always equals the number of protons in the nucleus?
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5. Metalloids have characteristics of both metals and nonmetals. [
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6. The number of protons in an atom's nucleus is called the atomic mass.
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7. lanthanides are placed below the main table in the periodic table. [
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8. Actinides are not radioactive. [
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9. Alkali metals are the least reactive group on the periodic table. [
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10. Transition metals are less reactive than alkali and alkaline-earth metals. [
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11. Covalent bonds are formed between atoms of non-metals. [
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12. In covalent bonding, valence electrons are transferred between two atoms. [
13. Covalent bonds can only be formed between atoms of the same element. [
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14. A molecule is formed when a group of two or more atoms are held together by ionic bonds. [
15. Hydrogen (H2) is an example of a compound molecule. [
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16. In a chlorine molecule (Cl2), each chlorine atom shares a pair of electrons. [
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17. Methane (CH4) is formed by four single covalent bonds between carbon and hydrogen atoms. [
18. Oxygen in carbon dioxide (CO2) shares two of its outer electrons. [
20. Substances with simple molecular structures are usually soluble in water. [
Subject: chemistry
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19. Substances with simple molecular structures have high melting and boiling points. [
Prepared by: Sakarye
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pg. 1
21. Most substances with simple molecular structures conduct electricity in any state. [
22. Giant molecular structures are usually soluble in organic solvents. [
23. Giant molecular structures have very low melting and boiling points. [
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24. Giant molecular structures are insoluble in both water and organic solvents. [
25. Acids turn blue litmus paper into red. [
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Section B: Matching fill in the blanks with the appropriate terms from the box (30 questions – 15 Marks).
1. What holds metal atoms together in a metallic lattice structure?
a) Covalent bonds b) Ionic bonds c) Metallic bonding d) Hydrogen bonds
2. What happens to the outer electrons of metal atoms in a metallic bond?
a) They gain electrons
b) They become positively charged ions
c) They become negatively charged ions
d) They become delocalized
3. What is responsible for the high electrical conductivity of metals?
a) Tight packing of atoms
b) Movement of mobile electrons
c) Formation of covalent bonds
d) Absence of electrons
4. Why do metals have high melting and boiling points?
a) Weak metallic bonds
b) Absence of mobile electrons
c) Strong electrostatic forces between ions and electrons
d) Lack of packing density
5. What property allows metals to be hammered into different shapes?
a) Ductility b) Conductivity c) Malleability d) Density
6. What happens to the arrangement of metal ions when a force is applied?
a) The ions break apart
b) The ions gain electrons
c) The ions slide over each other
d) The ions repel each other
7. What term describes the ability of metals to be drawn into wires without breaking?
a) Malleability b) Conductivity c) Ductility d) Rigidity
8. What is the primary reason behind the high densities of metals?
a) Loose packing of atoms
c) Strong metallic bonds
Prepared by: Sakarye
b) Movement of mobile electrons
d) Lack of electron cloud
Subject: chemistry
pg. 2
9. What enables heat energy to be easily transferred in metals?
a) Movement of mobile electrons
c) Tight packing of atoms
b) Absence of metallic bonds
d) Weak electrostatic forces
10. What term describes the situation where outer electrons move freely within the metal lattice?
a) Ionization
b) Delocalization
c) Polarization
d) Dissociation
11. Which solvent are substances with simple molecular structures typically soluble in?
a) Water b) Ethanol c) Dichloromethane d) Both a and b
12. Covalent bonds are typically formed between atoms of:
a) Metals
b) Noble gases
c) Non-metals
d) Alloys
13. Which of the following is an example of a compound molecule?
a) Hydrogen (H2)
b) Oxygen (O2)
c) Chlorine (Cl2)
d) Carbon dioxide (CO2)
14. In a hydrogen molecule (H2), how many single covalent bonds are formed?
a) None b) One
c) Two
d) Three
15. How many electrons are shared between two chlorine atoms in a chlorine molecule (Cl2)?
a) One b) Two
c) Three d) Four
16. What type of bond is formed in a molecule of oxygen (O2)?
a) Single covalent bond
b) Double covalent bond
c) Triple covalent bond
d) Ionic bond
17. How many single covalent bonds are formed between hydrogen and oxygen atoms in a water molecule
(H2O)?
a) None b) One
c) Two
d) Three
18. Which element forms a double covalent bond with itself in a molecule?
a) Hydrogen
b) Carbon
c) Nitrogen
d) Oxygen
19. What is the primary reason for the low melting and boiling points of substances with simple molecular
structures?
a) Strong covalent bonds
Prepared by: Sakarye
b) Weak intermolecular forces
c) Presence of metallic bonds
Subject: chemistry
d) High density
pg. 3
20. Why do substances with giant molecular structures have high melting and boiling points?
a) Due to weak intermolecular forces b) Because of strong metallic bonds
bonds d) Due to lack of intermolecular forces
c) Because of strong covalent
Section C: Direct Questions (40 Marks)
1. What is an acid? 2 marks
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2. What is the role of water in acids? 2 marks
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3. What electrostatic force of attraction? 2 marks
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4. What is the definition of a molecule? 2 marks
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5. Can you provide examples of compounds formed by covalent bonds? 2 marks
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6. What type of bond is formed when two electrons are shared between atoms of the same element? 2 marks
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7. What is the molecular formula of chlorine gas? 2 marks
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8. How many electrons are needed for oxygen atoms to achieve stable octet configuration in a molecule of
oxygen gas (O2)? 2 marks
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9. What is the molecular formula of nitrogen gas? 2 marks
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10. what are Noble Gases? 2 marks
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11. What is the molecular formula of methane? 2 marks
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12. How many electrons are needed for a carbon atom to achieve octet configuration? 2 marks
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Prepared by: Sakarye
Subject: chemistry
pg. 4
13. What is the difference between cations and anions? 2 marks
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14. Why do substances with giant molecular structures have high melting and boiling points? 2 marks
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15. Why do atoms react? 2 marks
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16. Explain ionic bonding? 5 marks
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17. Explain uses of sulfuric acid? 5 marks
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Section C Structural Questions: ( 3 questions – 15 Marks).
Using the first example as a guide complete the diagrams below by filling in the blanks.
Example: Methane (CH4)
‘Dot and cross’
diagram
H
H
H
Prepared by: Sakarye
Molecular
formula
Model
H
H
C
H
Structural
formula
C
H
H
H
Subject: chemistry
CH4
H
pg. 5
C
H
H
Oxygen
‘Dot and cross’
diagram
Structural
formula
Molecular
formula
Model
O
O2
Nitrogen
‘Dot and cross’
diagram
Structural
formula
Molecular
formula
Model
N
N
Carbon dioxide
‘Dot and cross’
diagram
Structural
formula
Molecular
formula
Model
C
O
CO2
Prepared by: Sakarye
Subject: chemistry
pg. 6