(x) A calcium ion (Ca²⁺) differs from a calcium atom (Ca) because a calcium ion has: A. Less electrons B. Less protons C. More electrons D. More neutrons

Match each item in List A with a correct response in List B by writing its letter below the number of the corresponding item in the table provided. LIST A LIST B (i) Burning gases that give out heat and light A. Boiling and filtration (ii) Coating iron objects using zinc metal B. Class C fire (iii) Domestic water treatment and C. Distillation purification (iv) Heterogeneous mixture D. Energy shell 1 (v) Holds maximum of 8 electrons E. Energy shell 2 (vi) Intelligent guess on the cause of the F. Experimentation problem (vii) Liquid metal G. Flame (viii) Relights a glowing splint H. Galvanization (ix) The burning material is a liquefied gas I. Hydrogen (x) Turns white anhydrous copper (II) J. Hypothesis sulphate blue K. Mercury L. Oxygen M. Solution N. Suspension O. Water Answers: LIST A i ii iii iv v vi vii viii ix x LIST B

1. Burning gases that give out heat and light (1 mk)
2. Coating iron objects using zinc metal (1 mk)
3. Domestic water treatment and purification (1 mk)
4. Heterogeneous mixture (1 mk)
5. Holds maximum of 8 electrons (1 mk)
6. Intelligent guess on the cause of the problem (1 mk)
7. Liquid metal (1 mk)
8. Relights a glowing splint (1 mk)
9. The burning material is a liquefied gas (1 mk)
10. Turns white anhydrous copper (II) sulphate blue (1 mk)

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Why most laboratory apparatuses are made of glass?

1. Why most laboratory apparatuses are made of glass? (2 mk)
2. Give two applications of chemistry in everyday life. (2 mk)
3. Differentiate between: (0 mk)
4. An atom and an element (2 mk)
5. Combustion and rusting (2 mk)
6. A solute and a solvent (2 mk)
7. A compound and a mixture (2 mk)

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Write the formula of each compound formed between: (i) Aluminium and chlorine (ii) Potassium and oxygen

1. Write the formula of each compound formed between: (0 mk)
2. Write the chemical symbols of the following elements: (0 mk)
3. Below is part of the periodic table and the numbers represent atomic numbers. Study the table carefully then answer the questions that follow: (0 mk)
4. Aluminium and chlorine (1 mk)
5. Potassium and oxygen (1 mk)
6. Boron (1 mk)
7. Silicon (1 mk)
8. Phosphorus (1 mk)
9. Write Z in group VI period 3 element. (1 mk)

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Explain safety measures that should be taken when handling chemicals with the following warnings: (i) Flammable (ii) Corrosive (iii) Irritant or Harmful (iv) Toxic

1. Explain safety measures that should be taken when handling chemicals with the following warnings: (0 mk)
2. (i) Name two reagents normally used for preparation of hydrogen in the laboratory. (2 mk)
3. (i) Why is hydrogen gas used for filling balloons? (1 mk)
4. Flammable (1 mk)
5. Corrosive (1 mk)
6. Irritant or Harmful (1 mk)
7. Toxic (1 mk)

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3. (a) Why do atoms combine? (b) A metal Z with atomic number 12 combines with chlorine to produce a metal chloride. By means of diagrams, illustrate the arrangement of electrons in Z before and after the reaction. (c) An atom X of atomic number 14 combines with chlorine to form a chloride. What type of bond will be formed between the atoms?

1. Why do atoms combine? (0 mk)
2. A metal Z with atomic number 12 combines with chlorine to produce a metal chloride. By means of diagrams, illustrate the arrangement of electrons in Z before and after the reaction. (0 mk)
3. An atom X of atomic number 14 combines with chlorine to form a chloride. What type of bond will be formed between the atoms? (0 mk)

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4. (a) What do you understand by the term "valency"? (b) Calculate the oxidation number of the underlined elements: (i) NaOH (ii) CO₃²⁻ (iii) Na₃PO₄ (iv) SO₂ (c) Explain three points on the importance of changing one state of matter to another.

1. What do you understand by the term "valency"? (0 mk)
2. Calculate the oxidation number of the underlined elements: (i) NaOH (ii) CO₃²⁻ (iii) Na₃PO₄ (iv) SO₂ (0 mk)
3. Explain three points on the importance of changing one state of matter to another. (0 mk)
4. Calculate the oxidation number of the underlined elements: SO₂ (1 mk)

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5. (a) Give two reasons why water is a compound. (b) Write IUPAC names for each of the following compounds: (i) CaCO₃ (ii) Al₂(SO₄)₃ (iii) NaHCO₃ (iv) Mg(NO₃)₂ (v) KCl (c) Describe a chemical test for water.

1. Give two reasons why water is a compound. (0 mk)
2. Write IUPAC names for each of the following compounds: (i) CaCO₃ (ii) Al₂(SO₄)₃ (iii) NaHCO₃ (iv) Mg(NO₃)₂ (v) KCl (0 mk)
3. Describe a chemical test for water. (0 mk)
4. Write IUPAC names for each of the following compounds: Mg(NO₃)₂ (1 mk)
5. Write IUPAC names for each of the following compounds: KCl (1 mk)

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6. (a) State the law of conservation of energy. (b) Give two ways in which energy can be transformed from one form to another. (c) List down two sources of heat in the laboratory.

1. State the law of conservation of energy. (0 mk)
2. Give two ways in which energy can be transformed from one form to another. (0 mk)
3. List down two sources of heat in the laboratory. (0 mk)

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7. (a) Define the term "empirical formula". (b) An organic compound contains 26.7% carbon, 2.2% hydrogen, and 71.1% oxygen. If its relative molecular mass is 90, determine its: (i) Empirical formula (ii) Molecular formula (c) State three points of modern atomic theory that amend Dalton’s ideas.

1. Define the term "empirical formula". (0 mk)
2. An organic compound contains 26.7% carbon, 2.2% hydrogen, and 71.1% oxygen. If its relative molecular mass is 90, determine its: (i) Empirical formula (ii) Molecular formula (0 mk)
3. An organic compound contains 26.7% carbon, 2.2% hydrogen, and 71.1% oxygen. If its relative molecular mass is 90, determine its: Empirical formula (4 mk)
4. State three points of modern atomic theory that amend Dalton’s ideas. (0 mk)

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