PRESIDENT OFFICE REGIONAL ADMNISTRATION
AND LOCAL GOVERNMENT
SECONDARY EXAMINATION SERIES
COMPETENCE BASED ASSEMENT
CHEMISTRY FORM THREE
ANNUAL EXAMINATIONS – 2023
032/1
Time: 3 Hours
Instructions
Atomic masses:
H=1, C=12, O=16, N=14, Ag=108
Avogadro’s number = 6.02 x 1023
GMV at s.t.p = 22.4 dm3
1 Faraday = 96,500 coulombs
Standard pressure = 760 mm Hg
Standard temperature = 273 K
1 litre = 1dm3 = 1000cm3
SECTION A. (16 MARKS)
LIST A | LIST B |
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SECTION B. (54 Marks)
Attempt all questions in this section
(b) An organic compound P consists of 52.2% carbon 13% hydrogen and 34.8% Oxygen. The vapour density of P is 23. Calculate molecular formula of the compound.
(c) Calculate Oxidation number of Nitrogen in potassium nitrate.
(b) 20.0cm3 of sodium hydroxide containing 8.0gdm3 was required for complete neutralization of 0.18g of dibasic acid. Calculate the relative molecular mass of the acid
(b) Dilute Silver Nitrate solution was decomposed by passage of electric current through it. What mass of Silver and what volume of Oxygen (measured at (STP) would be liberated in electrolysis by 9650C of electricity?
(b)Consider the equation below for dissociation of Suphuric acid
H2SO4(aq) → 2H(aq)+ + SO42-(aq)
From equation, how many ions are there in 9.8g of sulphuric acid?
16O8, 19F9, 20Ne10 23Na11 24Mg12. Atoms and ions of these elements can be 150-electronic (have same number of electrons)
(b)Although Sulphur dioxide is an Oxide, It can be further Oxidized
SECTION C (30 Marks)
Answer any two questions from this section
(b) State four uses of sodium metal
(b) Fire extinguisher is used to stop fire. List five types of fire extinguishers
(b) With the acid of chemical equation, briefly describe the following processes
LEARNINGHUBTZ.CO.TZFORM THREE CHEMISTRY MODAL SERIES 35
THE PRESIDENT’S OFFICE MINISTRY OF EDUCATION, REGIONAL ADMINISTRATION AND LOCAL GOVERNMENT
COMPETENCY BASED SECONDARY EXAMINATION SERIES
CHEMISTRY -SEPT 2022
FORM THREE
032
Time: 3 Hours SEPT, 2022
Instructions
questions.
Atomic masses: H = 1, O = 16, C = 12, N = 14, Na = 23, Cl = 35.5, K = 39
Ca = 40
Avogadro’s number:
GMV at s.t.p =
1 Faraday = 96,500 coulombs.
Standard pressure = 760 mm Hg.
Standard temperature = 273 K.
1 litre = =
SECTION A (15 Marks)
Answer all questions in this section.
A: spirit lamp B: gas stove C: kerosene stove
D: candle E: hurricane lamp
A: it is commonly known liquid
B: it exists in all three states of matter
C: it dissolves more substances than any other known liquid.
D: it is used for cooking, drinking and washing bodies and clothes
E: it is colourless, odourless and tasteless liquid
A: dilute hydrochloric acid B: cucumber C: lemon
D: tamarind E: blueberries
A: group I period 3 B: group VII period 2 C: group I period 7
D: group VII period 1E: group VII period 3
A: condensation B: melting C: evaporation
D: sublimation E: deposition
A: evaporating dishB: test tube holder C: deflagrating spoon
D: gas jar E: desiccator
A: sodium metal B: alloy C: water vapour
D: oil E: grease
A: fractional distillation B: filtration C: condensation
D: crystallization E: simple distillation
A: +1 B: 4 C: -1 D: +4 E: -2
A: aluminium B: calcium C: sodium
D: potassium E: both A and C
List A | List B |
| A: Electrovalent compound B: Potassium C:Bromine D: Covalent compound E:Phosphate F:Noble gases G:Metalloids |
SECTION B (70 Marks)
Answer all questions in this section
(a)(i) Write the actual names of element X, Y and compound Z.
(ii) What is the chemical combination involved in this interaction?
(b) (i) Draw the structure of the compound Z
(ii) Give two properties of compound Z.
three reasons to support this statement.
(b) With the help of balanced chemical equation, explain what will happen to:
(i) A piece of iron bar left to the exposure.
(ii) Anhydrous copper (II) sulphate when put into the watch glass and placed
on the laboratory bench.
(ii) Write the symbols of phosphorous, fluorine, manganese and copper.
(b) Why some elements are assigned symbols with only one letter while
Others bear with two letters?
Chloride hexahydrate.
(ii) Why laboratory safety precaution is very important?
(b) Categorize the following laboratory compounds into corrosive and flammable:
Sodium hydroxide, spirit, sulphuric acid, oil, aro and benzene
bythermal decomposition of potassium chlorate. If he used 20g of potassium
chlorate, what volume of oxygen would be produced at s.t.p?
products.
wood.
(b) (i) “Liquid fuel is more advantageous than solid fuel”. Give three points to
support this statement.
(ii) Write down the composition of water gas and producer gas.
Write the reactions which take place at the electrodes and give reason why
the solution becomes alkaline.
electricity for one and a half hours?
SECTION C (15 Marks)
Answer one (1) question in this section.
Page 1 of 5
LEARNINGHUBTZ.CO.TZFORM THREE CHEMISTRY MODAL SERIES 31
THE PRESIDENT'S OFFICE
MINISTRY OF REGIONAL GOVERNMENT AND LOCAL GOVERNMENT
AUGUST-SEPTEMBER EXAMINATION SERIES
CHEMISTRY FORM-3
2020
TIME: 2:30 HRS
Instructions
Atomic masses: H 1, O- 16, N- 14, S = 32, Zn - 65, Cl -35.5, cu - 64.
Avogadros number= 6.02 x 1023
GMV at s.t.p =22.4 dm3 .
1 Faraday= 96,500 coulombs.
Standard pressure = 760 mm Hg. Standard temperature 273 K.
1 litre =1 dm3 =1000 cm 3.
SECTION A (15 Marks)
Answer all questions in this section.
1. For each of the items (i) — (x), choose the correct answer from among the given alternatives and write its letter beside the item number in the answer booklet provided.
(i) "Water is referred to as the universal solvent". What does this mean?
(ii) What is the proper set of apparatus would you use to grind granules of a solid substance into fine powder in the laboratory?
(iii) Which of the following sets of processes uses a gas that ignites with a "pop" sound when a lighted splint is passed through it?
(iv) A current of 0.2 A was passed through an electrolyte for 16 minutes and 40 seconds. What is the quantity of electricity produced in coulombs?
(v) Aluminium does not react with water and does not corrode much in air because
(vi) When a burning fuel produces blue color it means there is
(vii) Which of these can be reduced when heated with carbon?
(viii) Which of the following is NOT among the composition of air?
(ix) If a steady current of 2 amperes was passed through an aqueous solution of iron (II) sulphate for 15 minutes, the mass of iron deposited at the cathode will be.
(x) Two substances are allotropes of carbon if
2. Match the descriptions in List A with the corresponding scientific procedures in List B by writing the letter of the correct response besides the item number in the answer booklet provided.
LIST 1 | LIST B |
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SECTION B (70 Marks)
Answer all questions in this section.
3. (a) How many chlorine molecules are in 20 cm of chlorine gas at s.t.p?
(b)Calculate the number of ions present in 5 g of copper II nitrate.
4. (a) Distinguish temporary hardness from permanent hardness of water.
(b) With the help of chemical equations, explain how you can remove each type of water hardness in 5(a).
5. (a) Copper obtained from copper pyrites (CuFeS2) is impure for electrical wiring and has to be purified by electrolysis.
(i) Name the electrolyte and the electrodes used during electrolysis.
(ii) Write the observations that can be made during the electrolysis.
(b) The following flow diagram shows the stages in the contact process
(i) Give the names of element A, catalyst B and an acid C.
(ii) Write a balanced chemical equation for the formation of sulphur trioxide in stage 2
6. (a) Give one example in each of the following:
(i) Alkali earth metals.
(ii) Noblegases .
(iii) Transition elements.
(b) Write the names of the following processes of changing matter from one state to another.
(i) Gas to liquid.
(ii) Ga s to solid.
(iii) Solid t o gas .
7. (a) State four steps employed in the extraction of moderate reactive metals.
(b) Write balanced chemical equations to show how chlorine reacts with the following:
8. (a) State three main physical properties of water and show the usefulness of each property.
(b) State three industrial application of electrolysis.
9. (a)An atom M has an atomic number 14 and mass number 28.
(i)What is the number of protons and neutrons?
(ii) Write the electronic configuration of atom M.
(b) Calculate the volume of water which was produced when 1,120 cm3 of oxygen at s.t.p. was liberated during the decomposition of hydrogen peroxide. The density of water = 1.0 g/cm3
10. (a) Determine the empirical formula of a substance that has the following composition by mass; 49.5% oxygen.
(b) Give one reason why Alluminium is chosen to make each of the following items:
11. (a) Identify and state the environmental problem caused by the gas which is released from the blast furnace in the extraction of iron from its oxide.
(b) (i) Draw a labeled diagram of a simple electrolytic cell which show how copper is purified.
(ii) Write balanced ionic equations to show the electrode reactions which occur when copper is purified.
12. (a) (i) Why chemistry laboratory exits open outward?
(ii) State the uses of any four items found in a First Aid Kit.
(b) (i) Arrange the following metals in order of increasing reactivity; zinc, magnesium, calcium, copper and mercury.
(ii) Which one of the metals in (b) (i) above reacts with steam to form an oxide which is white when cold and yellow when hot?
SECTION C (15 Marks)
Answer one (1) question from this section.
13. In Tanzania, soil conservation is very important for Industrial Materials production. Explain six methods that are used to manage loss of plant nutrients from the soil.
14. 0.48g of a metal, M was placed in a test tube and hot copper (II) sulphate solution was added to it and stirred until the reaction stopped. The metal (M) displaced copper from copper (II) sulphate solution. Copper was filtered, washed with water, dried at 1000 C and the mass found to be 1.27g. Given that, the balanced chemical reaction that occurred is M (s) + CuSO 4(aq) MSO 4(aq) + Cu (s)
(a) Calculate;
(b) State the appearance of the metal formed (Cu).
(c) With ionic equations, explain why the reaction can be considered to involve both oxidation and reduction.
LEARNINGHUBTZ.CO.TZFORM THREE CHEMISTRY MODAL SERIES 25
MODEL EXAMINATION PAPER 2
CHEMISTRY F3
NAME………………………………….………………..CLASS…………………………….……………TIME: 3HRS
INSTRUCTIONS:-
1. This paper consists of sections A, B and C
2. Answer all questions in all sections
3. Whenever necessary, the following constructs may be used.
SECTION A (15 marks)
(i) All domestic utensils made of iron undergo rusting when exposed to:-
(ii) When a small amount of common salt is dissolved in a glass of water the mixture formed is:-
(iii) A chemist should acquire all of the following skills EXEPT:-
(iv) An important property of oxygen which distinguishes it from other gases is that it:-
(v) The process of chlorination in water treatment aims at:-
(vi) One of the following is not correct about coke being a better fuel than coal as it:-
(vii) Class E fire can best be extinguished by using:-
(viii) The following is a set of apparati which are used for heating:-
(ix) Which of the following methods can be used to get oil from cotton seeds?
(x) Which of the following apparati is suitable for measuring volumes of smaller quantities of liquids?
LIST A | LIST B |
(i) Chemical equation (ii) Liquid metal (iii) Ammonia (iv) Deliquescent (v) X2+ + 2 e- X |
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SECTION B (54 marks)
(b) Write down the names and formulae of three common acids in the laboratory.
(c ) What is an indicator? Give four (4) examples of acid- base indicators.
(d) Write down the products formed when each of following pairs of compounds react:
(i) Acid and metal
(ii) Acid and metal carbonate (10 marks)
(i) CaCO3(s) + heat
(ii) K2CO3 (s) + HCl (aq)
(iii) Pb (NO3)2 (aq) + Na2 SO4 (aq)
(b) Write a balanced chemical equation and its corresponding ionic equation for the reaction between dilute sulphuric acid and:-
(i) Sodium hydroxide solution.
(ii) Zinc granules.
N.B. show all the state symbols. (10 marks)
(b) Calculate the molar mass of (i) Al2 (SO4)3 (ii) Na2 Co3 10H2O
( c) State the Avogadro’s law
(d) How many oxygen molecules are there in 20cm3 of oxygen gas at STP?(10 marks)
(ii) Name two types of flames produced by the Bunsen burner
(iii)How do the two above mentioned flames differ?
(b) Write down four (4) careers that are a result of studying chemistry.(10 marks)
(a) (i) Label the parts indicated with letters A, B, C, D in the diagram
(ii) Does Oxygen burn? Why?
(b) The formula of manganese (iv) oxide is MnO2 and that of hydrogen peroxide is H2O2. Which compound produces oxygen?
(c) (i) What is the name of the method of collection the gas?
(ii) Explain the meaning of catalyst.
(iii)How can you test for oxygen? ( 10 marks)
Note: The letters used are not the scientific symbols for the elements concerned .
I O | |||||||
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(A) Identify and write down the electronic configuration for the elements K,N,P and L
(B) What type of bond will exist in a compound formed when Q combines with L? write the chemical formula for the compound formed and list two chemical properties of the compound formed. ( 10 marks)
9. Zinc metal and hydrochloric acid reacts according to the equation below;
Zn(s) + 2HCl(aq) ZnCl2(aq) + H2(g)
3.12g of Zn metal were reacted with 200cm3 of 0.1M hydrochloric acid
(i) Determine the reagent that was in excess
(ii) Calculate the total volume of hydrogen gas liberated at standard temperature and pressure.( Z=65.4, Molar gas volume = 22.4 litres at S.T.P) (10 marks)
SECTION C (15 marks)
(b) Copy and complete the passage about the manufacture of sulphuric acid.
Note: Underline your answers.
Passage:-
Sulphuric acid is made by contact process.
First sulphur or sulphur - containing compounds are burned in air to produce ________gas.
This gas is purified to prevent the catalyst being_____________at a later stage.
This gas and air are passed over a _____________catalyst to produce sulphur trioxide.
Sulphur trioxide dissolves in concentrated sulphuric acid to produce_______________.
This is diluted with_______________ to produce an ordinary concentrated sulphuric acid.
(b) The industrial preparation of ammonia in the Haber process is represented by the following equation:
N2(g) + 3H2(g) catalyst 2NH3(g) H= -46.2KJ/mol
Study the equation carefully then answer the questions that follow:
What will happen to the position of equilibrium if:
(i) The temperature of the equilibrium mixture is increased?
(ii) More Nitrogen gas is added to the equilibrium mixture?
(iii) The formed ammonia is removed from the equilibrium mixture?
(c ) What is the use of catalyst in the reaction in 10(b) above?
(d) What is the meaning of the negative sign against the value of heat change -46.2KJ/mol in the chemical reaction given in 10(b) above?
(e) Sketch an energy profile diagram against reaction in 10(b) above.
LEARNING HUB.TZ Page 1
LEARNINGHUBTZ.CO.TZFORM THREE CHEMISTRY MODAL SERIES 13
MODEL EXAMINATION PAPERS
CHEMISTRY FORM THREE
MODEL PAPER 1
NAME…………………………………..CLASS…………………………….……………………TIME 3HOURS
INSTRUCTIONS:-
- This paper consists of three sections- A, AND B
- Answer all questions in section A and B.
- This paper consists of section A, B, and C
- Answer all questions
- You may use the following constants: Na = 23, C = 12, O = 16, IGMV = 22.4dm3 IF = 96500C, NA = 6.02 X 1023
SECTION A.
(i) How would you protect yourself from direct contact with corrosive chemical in the lab?
(ii) What is the use of a funnel?
(iii) Which part of a blue Bunsen flame is not so hot?
(iv) Which set of compounds have names ending in ide?
(v) Which of the following is not a homogenous mixture?
(vi) Which method is used to separate oxygen from air?
(vii) What is term used for a substance resulting from condensation process?
(viii) What is the colour of phenolphthalein in alkali solution?
(ix) Which substance will change wet litmus paper from blue to red?
(x) Which substance produce a pH of 14 when tested
i | ii | iii | iv | v | vi | vii | viii | ix | x |
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SECTION B.
Numbered item:
(i) Normal salt
(ii) Crystallization by boiling
(iii) Nonsense combination of ions for a formula
(iv) Most reactive elements in the periodic table
(v) Another name for inert gases
Lettered items
(b) What is the effect of temperatures above 800°C in process (a) above?
(c) How can the temperature of 800°C be lowered to 600°C?
(a) Aqueous sodium carbonate reacts with dilute hydrochloric acid
(b) Silver nitrate solution reacts with dilute magnesium chloride solution
(c) Zinc metal is put in a solution of copper sulphate
(d) Barium chloride solution reacts with sodium sulphate solution
(e) Calcium metal is reacted with cold water
(b) Compound Q was found to have the molar mass of 106 with the following percentage composition by mass 43.4% sodium, 11.3% carbon, 45.5% oxygen. Find the molecular formula of the compound Q and write its chemical name.
(a) Which of the solutions:
(i) Is exactly neutral
(ii) Is strong acidic
(iii) Is weakly alkaline
(b) Could be a solution of carbon dioxide in water
(c) Will give universal indicator colour (i) Green (ii) Red
(d) Will contain a large concentration of OH ions
(e) Could be a solution of ammonia in water?
(i) NaClO3
(ii) K1O3
(iii) NaH
(iv) Ca(NO3)
(v) NO
(b) Write the chemical formula of the following compounds
(i) Lead (II) chloride
(ii) Aluminium hydride
(iii) Sodium hydrogen phosphate (v)
(iv) Sulphur oxide (VI)
(v) Ammonium chloride
SECTION C
(b) With the help of an energy level diagrm on the reaction
CaCO3 CaO(g) + CO2(g)
∆H = + 175.5 kJ. Mol -1
(i) Show weather the reaction is exothermic or endothermic
(ii) Write down the type of the reaction shown by the above equation
(c) What will be the effect on the proportion of calcium carbonate in the equilibrium mixture in the above equation if
(i) The temperature is increased?
(ii) The pressure is increased?
(b) An electric current was passed in series through solutions of calcium chloride and copper (II) sulphate using carbon electrodes in the electrolytes. If 2.5dm3 of chlorine gas was collect at stp what volume of oxygen and what mass of copper were formed at the same time?
N2(g) + 3H2(g) 2NH3(g) + 46.2 kJ. mol-1
By the help of a well labeled diagram explain how the above process takes place under the influence of
(i) Temperature
(ii) Pressure
(iii) Catalyst.
LEARNING HUB.TZ Page 1
LEARNINGHUBTZ.CO.TZFORM THREE CHEMISTRY MODAL SERIES 12
MODEL EXAMINATION PAPERS
CHEMISTRY FORM THREE
MODEL PAPER 1
NAME…………………………………..CLASS…………………………….……………………TIME 3HOURS
INSTRUCTIONS:-
- This paper consists of three sections- A, AND B
- Answer all questions in section A and B.
- This paper consists of section A, B, and C
- Answer all questions
- You may use the following constants: Na = 23, C = 12, O = 16, IGMV = 22.4dm3 IF = 96500C, NA = 6.02 X 1023
SECTION A.
(i) How would you protect yourself from direct contact with corrosive chemical in the lab?
(ii) What is the use of a funnel?
(iii) Which part of a blue Bunsen flame is not so hot?
(iv) Which set of compounds have names ending in ide?
(v) Which of the following is not a homogenous mixture?
(vi) Which method is used to separate oxygen from air?
(vii) What is term used for a substance resulting from condensation process?
(viii) What is the colour of phenolphthalein in alkali solution?
(ix) Which substance will change wet litmus paper from blue to red?
(x) Which substance produce a pH of 14 when tested
i | ii | iii | iv | v | vi | vii | viii | ix | x |
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SECTION B.
Numbered item:
(i) Normal salt
(ii) Crystallization by boiling
(iii) Ionic reactions
(iv) Absorbs moisture to form a solution
(v) A more soluble salt
(vi) Softened by boiling
(vii) Nonsense combination of ions for a formula
(viii) Molecular formula
(ix) Most reactive elements in the periodic table
(x) Another name for inert gases
Lettered items
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(b) What is the effect of temperatures above 800°C in process (a) above?
(c) How can the temperature of 800°C be lowered to 600°C?
(a) Aqueous sodium carbonate reacts with dilute hydrochloric acid
(b) Silver nitrate solution reacts with dilute magnesium chloride solution
(c) Zinc metal is put in a solution of copper sulphate
(d) Barium chloride solution reacts with sodium sulphate solution
(e) Calcium metal is reacted with cold water
(b) Compound Q was found to have the molar mass of 106 with the following percentage composition by mass 43.4% sodium, 11.3% carbon, 45.5% oxygen. Find the molecular formula of the compound Q and write its chemical name.
(a) Which of the solutions:
(i) Is exactly neutral
(ii) Is strong acidic
(iii) Is weakly alkaline
(b) Could be a solution of carbon dioxide in water
(c) Will give universal indicator colour (i) Green (ii) Red
(d) Will contain a large concentration of OH ions
(e) Could be a solution of ammonia in water?
(i) NaClO3
(ii) K1O3
(iii) NaH
(iv) Ca(NO3)
(v) NO
(b) Write the chemical formula of the following compounds
(i) Lead (II) chloride
(ii) Aluminium hydride
(iii) Sodium hydrogen phosphate (v)
(iv) Sulphur oxide (VI)
(v) Ammonium chloride
SECTION C
(b) With the help of an energy level diagrm on the reaction
CaCO3 CaO(g) + CO2(g)
∆H = + 175.5 kJ. Mol -1
(i) Show weather the reaction is exothermic or endothermic
(ii) Write down the type of the reaction shown by the above equation
(c) What will be the effect on the proportion of calcium carbonate in the equilibrium mixture in the above equation if
(i) The temperature is increased?
(ii) The pressure is increased?
(b) An electric current was passed in series through solutions of calcium chloride and copper (II) sulphate using carbon electrodes in the electrolytes. If 2.5dm3 of chlorine gas was collect at stp what volume of oxygen and what mass of copper were formed at the same time?
N2(g) + 3H2(g) 2NH3(g) + 46.2 kJ. mol-1
By the help of a well labeled diagram explain how the above process takes place under the influence of
(i) Temperature
(ii) Pressure
(iii) Catalyst.
LEARNING HUB.TZ Page 1
LEARNINGHUBTZ.CO.TZFORM THREE CHEMISTRY MODAL SERIES 1