2. Pb (N0₃)₂

3. H2 S0₄ + KOH

4. CUCO₃

5. Na + H₂O

6. With the aid of a well balance chemical equations explain what would happen in each of the following reactions

   1. Potassium carbonate is strong heated

   2. Concentrated sulphuric acid added to dry salt and heated

   3. Sodium nitrate heated

   4. Concentrated sulphuric acid slowly acted to the sugar

   5. Soluble alkali added to the soluble salts

   6. Carbon dioxide passed through lime water

   7. Water is added to a white copper (11) sulphate

   8. A glowing splint of wood is lowered into a jar of (i) Hydrogen gas (ii) Carbon dioxide gas

   9. Ammonium chloride is heated

   10. Dilute nitric acid was heated with (i) warm copper oxide (ii) Zinc carbonate

7. Write the product and balance the following chemical equations

   1. Ag N0_3(aq) + NaCl_(aq)

   2. Zn_(s) + H₂S0_4(aq)

   3. MgCl_2(aq) + AgN0_3(aq)

   4. Na₂S0_4(aq) + BaCl_2(aq)

   5. ZnC0_3(s) + HCl_(aq)

   6. Na_(s) + H₂0_(l)

8. Complete and balance the following chemical equations:-

1. Fe(OH)₃ + H₂ SO₄

2. MgCO₃ + HCl

3. Na + O₂

4. H₃PO₃ + Al₂O₃

9. Explain the meaning of each of the following types of chemical reactions and support your explanation with the help of a relevant chemical equation.

1. Synthesis (combination) reaction

2. Decomposition reaction

3. Precipitation reaction

4. Single displacement reaction

5. Neutralization reaction

10. (a) Define:-

1. Redox reaction

2. Oxidation reaction

3. Reduction reaction

(b) Classify the following reactions into oxidation and reduction reactions:-

1. S_(s) + O_2(g) SO_2(g)

2. N_2(g) + 3H_2(g) 2NH_3(g)

3. Fe²⁺ _(aq) – e^- Fe³⁺_(aq)

4. Fe³_(aq) + e^- Fe²⁺_(aq)

(c) Write the balanced equations for the following reactions.

(i) Hydrogen + chlorine Hydrogen chloride

(ii) Magnesium oxide + carbon Magnesium + carbon monoxide

(iii)Silver nitrate + sodium chloride silver chloride + sodium nitrate

11. (a) Explain the meaning of “an ionic equation”

(b) Write an ionic equation for each of the following:

1. Carbon dioxide gas dissolves in an aqueous solution of potassium hydroxide

2. The reaction between magnesium and dilute hydrochloric acid.

LEARNING HUB.TZ

CHEMISTRY EXAMINATION FORM THREE

TOPICAL EXAMINATIONS.

HARDNESS OF WATER

NAME………………………………………..CLASS…………………………………………….……………TIME: 2¹/₂HRS

INSTRUCTIONS:-

1. This paper consists of sections A, B and C

2. Answer all questions

3. All answers must be written in the spaces provided

4. All writings should be in blue/black inks except for drawings that should be in pencils

SECTION A 20 MARKS.

1. Hard water which can be softened by boiling method contains dissolved:-

1. Calcium Hydrogen sulphate

2. Magnesium chloride

3. Magnesium carbonate

4. Calcium sulphate.

2. Which of the following compounds can be used to remove hardness of water?

1. Calcium chloride

2. Sodium carbonate

3. Magnesium hydroxide

4. Potassium hydroxide

5. Zinc chloride.

3. ……………….. Is a one of the substance whose dissolution in water caused permanent hardness?

1. Carbon dioxide

2. Calcium sulphates

3. Magnesium carbonate

4. Sodium carbonate

4. One of the disadvantages of hard water is that is;

1. Causes corrosion of water pipes

2. Causes increased tooth decay

3. Requires more soap for washing

4. Contains minerals that are harmful

5. Hard water which is softened just by boiling contains dissolved;

1. Calcium carbonate

2. Calcium chloride

3. Sodium carbonate

4. Magnesium sulphate

5. Calcium hydrogen carbonate

6. Which of the following methods can be used to remove both temporary and permanent hardness of water.

1. Using ion exchange chamber

2. Boiling

3. Using of calcium hydroxide

4. Evaporation

7. Which of the following is not an advantage of hard water?

1. Suitable for drinking

2. Strengthens bones and teeth

3. Suitable for brewing of beer

4. Makes our teeth coloured

8. One advantage of soft water is that;

1. Forms lather with soap

2. Suitable for drinking

3. Has a nice taste

4. Used in treatment of ulcers

9. Which is the best method that removes hardness of water to a large extend?

1. Boiling

2. Distillation

3. Using washing soda

4. Using calcium hydroxide

10. The main source of salt water on earth is;

1. Sea

2. Springs

3. Glaciers

4. Wells

2. Matching Items Questions.

3. Write down the chemical equations used when softening water of the

1. Temporary hardness through (i) boiling water (one question) (ii) use of chemicals (two equations)

2. Permanent hardness through (i) use of chemicals (one equation) (ii) iron exchange (one equation)

3. Define the following terms;

1. Soft water

2. Hard water

3. Permanent hardness of water

4. Temporary hardness of water

3. a) What is the hardness of water?

b) Briefly explain types of hard of water.

c) State the causes of hardness of water for each type mention in (b) above.

d) Explain how you would remove the hardness of water according to its type.

e) Give three (3) advantages and three (3) disadvantages of the hard water.

3. Soap solution of different amount of water are tested from four different sources and produces lather observed for 30 seconds. The three groups of waster were the untreated; boiled and treated by ion exchange. The results are as follows;

Sample	Volume of soap (cm3) used for water that was
	Untreated	Boiled	Passed through ion exchanger
A B C D	12 17 26 1.6	1.8 17 20 1.6	1.8 1.7 1.8 1.6

Use the above results to answer the following questions;

1. Which is the hardest water sample? Why?

2. Which sample is like distilled water? Explain.

3. Which chemical substance might be the cause of hardness in (i) Sample A (ii) Sample B?

4. Write an equation for the reaction of removing hardness in sample C.

3. (a) State two advantages of hard water.

(b) State two disadvantages of hard water.

(c) Give two methods of softening temporary hardness of water.

3. (a) Distinguish between;

1. Acidic salt and basic salt

2. Hydrated and anhydrous salt

(b) Vinegar, lemon juice and yoghurt all have sour taste. Give the other possible properties would you expect them to have? Give 3 points.

3. (a) Give meaning of the following;

1. Basicity of an acid

2. The pH scale

(b) Name substances which when dissolved in water causes;

i. Temporary hardness of water

ii. Permanent hardness of water

(c) Explain with the help of one chemical equation in each case how?

i. Temporary hardness of water can be removed by boiling. (3 marks)

ii. Permanent hardness of water can be removed by chemical means.

3. Give a brief account to the following

1. Why does water note have any effect on litmus paper?

2. (i) What would happen to a well stoppered bottle full of water left in a deep freezer over the night? Why does this happen?

(ii) Why is iron not usually recommended in the construction of steam pipes and boilers.

3. (i) Name two compounds which may cause temporary hardness of water and two

ions which largely cause permanent hardness of water.

(ii) Write one balanced chemical equation which shows how temporary hardness can be removed by boiling. Also write one balanced equation which shows how sodium carbonate can be used to remove permanent hardness of water.

3. (a) What do you understand by the following terms:-

1. Abase (ii) Alkali (iii) Weak acid (iv) Hygroscopic substance.( 2 marks)

(b) With the aid of chemical equation describe how permanent and temporary hardness of water can be removed?

1. (a) State two advantages of hard water.

(b) State two disadvantages of hard water.

(c) Give two methods of softening temporary hardness of water.

LEARNING HUB.TZ

CHEMISTRY EXAMINATION FORM THREE

TOPICAL EXAMINATIONS.

ACID BASES AND SALTS

NAME………………………………………..CLASS…………………………………………….……………TIME: 2¹/₂HRS

INSTRUCTIONS:-

1. This paper consists of sections A, B and C

2. Answer all questions

3. All answers must be written in the spaces provided

4. All writings should be in blue/black inks except for drawings that should be in pencils

1. MULTIPLE CHOICE QUESTIONS

1. Sea water contains various salts. Which salt is present in the largest proportion?

1. Magnesium sulphate

2. Sodium chloride

3. Calcium sulphate

4. Magnesium chloride

2. Which pair among the following comprises of good drying agents?

1. Calcium carbonate and lead (II) chloride

2. Anhydrous calcium chloride and concentrated sulphuric acid

3. Calcium sulphate and calcium oxide

4. Concentrated nitric acid and concentrated hydrochloric acid

3. A weak acid is the best describe as ……………………..

1. An acid that does not ionize completely.

2. A dilute acid.

3. An acid that does not react with any substance.

4. An acid that is harmless.

4. When dilute solutions of calcium chloride and sodium carbonate are mixed;

1. A white precipitate of sodium chloride is formed

2. A white precipitates of calcium carbonate is formed

3. A colourless solution of calcium carbonate and sodium chloride are formed

4. A mixture of precipitates of sodium chloride and calcium carbonate are formed.

4. Insoluble salts like lead (II) chloride, generally can be obtained in the laboratory by;

1. Crystallization

2. Precipitation

3. Decomposition

4. Evaporation of its concentrated solution

4. A hygroscopic substance;

1. Evaporates to the air

2. Loses water to the air

3. Add water to a compound

4. Absorbs moisture from the air

5. Removes elements of water from a compound

4. An efflorescent substance;

1. Evaporates to the air

2. Loses water to the air

3. Absorbs moisture from the air

4. Removes elements of water from a compound

5. Adds water to a compound

4. Which of the following is a weak acid?

1. Sulphuric acid

2. Hydrochloric acid

3. Ethanoic acid

4. Nitric acid

4. A solution of a PH of 1 is said to be;

1. Slightly acidic

2. Slightly basic

3. Strong acid

4. Neutral

4. Which of the following is not a product when silver nitrate is heated?

1. Silver oxide

2. Silver metal

3. Nitrogen dioxide gas

4. Oxygen gas

2. Matching items questions.

3. A) Acids can react with, carbonates, hydrogen carbonates, oxide and hydroxide. Presence of carbon dioxide can be proved using lime water. Support the above statements by using balanced chemical equations.

   B) How can one prepare a flower extract indicator and use it?

4. Distinguish between the following terms

   1. Hydrate salts and unhydrate salts

   2. Efflorescence and deliquescence

   3. Base and alkali

   4. Acid and base

   5. Acid salts and normal salts

5. Fill the following tables

Table one.

Table Two.

6. (a) 416g of anhydrous barium chloride where obtained when 488g of hydrated salt were heated.

Calculate the value of n is the formula BaCl₂.nH₂O (Ba = 137)

(b) Give the meaning of the following;

(i) An acid

(ii) Molar solution of an acid

(iii) Give three characteristics of acid.

7. Differentiate salts behave differently when heated. Complete the following equations that show the actions of heat on certain salts;

1. PbCO_3(s)

2. 2Ca (NO₃)_2(s)

3. (NH₄)₂ CO_3(s) 2NH_3(g)⁺

4. NH₄Cl_(s)

8. (a) Distinguish between strong acid and weak acid

   (b) Explain three applications of neutralization

9. 25cm³ of potassium hydroxide were placed in a flask and a few drops of phenolphthalein indicator were added. Dilute hydrochloric acid was added until the indicator changed colour. It was found in the 21cm3 of acid were used.

   From above information answer the following questions;

   A: (i) What piece of apparatus should be used to measure out accurately 25cm³ of sodium hydroxide solution?

   (ii) What color was the solution in the flask at the start of the titration?

   (iii) What color did it turn when the alkali had been neutralized?

   B: (i) Was the acid more concentrated or less concentrated than the alkali?

   (ii) Name the salt formed in the neutralization.

   (iii) Write an equation for the reaction.

   (iv) Is the salt, normal or acidic salt? Give reasons for your answer.

   C: (i) Utilizing the given information of question 9 (a) and (b) above describe how you can obtain pure crystals of the salt.

   (ii) Is it a soluble salt or insoluble salt? Give a reason for your answer.

10. A sample of water forms scum with soap. When the water was boiled and then cooled it still formed scum.

1. Does this water have temporary hardness or permanent hardness?

2. Suggest one treatment that can be used to soften the water.

11. (a) Define the term indicator.

(b) Write only two uses of pH scale.

(c) Write two uses of salts.

12. (a) Give meaning of the following;

1. Basicity of an acid

2. The pH scale

(b) Name substances which when dissolved in water causes;

i. Temporary hardness of water

ii. Permanent hardness of water

(c) Explain with the help of one chemical equation in each case how?

i. Temporary hardness of water can be removed by boiling.

ii. Permanent hardness of water can be removed by chemical means.

3. (a) Differentiate between basic salt and acidic salt.

(b) Categorize the following salts;

i. PbSO4 ii. MgHSO₄ iii.Zn(OH)Cl iv. MgHCO₃

v. NH₄HSO₄ vi. Ba(NO₃)₂

Salts	Category

13. (a) Define the term “neutralization reaction” (give one example)

(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

14. (a) Name of element found in all acids

(b) Describe two tests you would carry out on a liquid to decide whether it is an acid or not in each case describe the test and result you would expect.

(c)If some acids spills on your clothes, which of the following substance would you put on the cloth to prevent further damage? Sodium hydroxide solution, sodium hydroxide pellets, concentrated ammonia solution or sodium hydrogen carbonate? Why?

LEARNING HUB.TZ

CHEMISTRY EXAMINATION FORM THREE

TOPICAL EXAMINATIONS.

ENERGY AND FUELS

NAME………………………………………..CLASS…………………………………………….……………TIME: 2¹/₂HRS

INSTRUCTIONS:-

1. This paper consists of sections A, B and C

2. Answer all questions

3. All answers must be written in the spaces provided

4. All writings should be in blue/black inks except for drawings that should be in pencils

5. MULTIPLE CHOICE QUESTIONS.

1. Which one of the following energy transformation can produce H.E.P?

1. Electrical energy changes to heat energy

2. Electrical energy changes to mechanical energy

3. Mechanical energy changes to Electrical energy

4. Mechanical energy changes to chemical energy

2. One of the following is not correct about coke being a better fuel than coal as it;

1. Does not produce carbon dioxide gas

2. Does not produce poisonous gas

3. Has a higher heat content [ ]

4. Is clean and smokeless

2. ___________is the characteristic of good fuels:-

1. Firewood

2. Easily available ( )

3. Melting

4. Ability to burn houses into ashes.

2. What is kindling temperature

1. A kind temperature

2. Temperature out of a burning material

3. The highest temperature obtained from a burning substance

4. The lowest temperature at which a combustible material can catch fire.

2. Which of the following is a renewable source of energy?

1. Coal

2. Petroleum

3. Biogas

4. Natural gas

2. Which of the following is not a primary source of energy?

1. Wood

2. Kerosene

3. Crude oil

4. Natural

2. Which of the following is not a characteristic of a good fuel?

1. Readily available

2. Should have low energy value

3. Should be affordable

4. Easy to transport

2. In production of hydroelectric power, which of the following is the best energy transformation?

1. Electric energy to heat energy

2. Electrical energy to mechanical energy

3. Mechanical energy to electrical energy

4. Chemical energy to electrical energy

2. Which of the following has a chemical energy?

1. Natural gas

2. Biomass

3. Coal

4. Solar energy

2. Which of the following is not an advantage of biogas?

1. It is cheaper source of energy

2. Pollutes the environment

3. It is renewable source of energy

4. Creates employment among the youth

6. Matching items questions

7. Electricity can be used to perform work also for heating purpose. Explain how it can happen and use four (4) practical examples in each case.

8. (a) What is fuel? ……………………………………………………………………………………………………………………………………………………………………………………………………

(b) Mention three categories of fuel and give two examples for each category.

(i) ………………………………………..

examples …………………………………. and ………………………………….

(ii) …………………………………………

examples ………………………………… and …………………………………

(iii) ……………………………………………

examples …………………………………. and ………………………………….

(c) The problem facing Tanzania society is misuses of charcoal and fire wood as a

source of fuel. Give two points of advice to the society on how to use less

charcoal and firewood efficiently.

9. (a) Write P for primary and S for secondary in the following fuels.

Wood……………. Petrol…………… Coal gas……………………….

(b) Which gaseous fuels are a result of the following processes?

(i) Destructive distillation of coal…………………………………….

(ii) Destructive distillation of wood…………………………..........

(iii)Air reacts with red hot coke at 1000⁰C……………………..

10. (a) Write the chemical symbol for each of the following elements.

1. Argon_________(ii)Lead________(iii)Silver__________(iv)Manganese____ (v) Barium______________(vi)Xenon_____________.

(b) Write the chemical formulae of the following compounds:-

1. Potassium sulphate

2. Copper (II) carbonate

3. Aluminium oxide

4. Magnesium hydroxide

11. Explain the major ways of obtaining artificial fuels from natural fuels in all the three states of matter.

12. By the help of a well labeled diagram explain how one can conduct an experiment on destructive distillation of coal.

13. (a) What is fuel

(b)Give two example of each of following categories of fuels

i) Solid fuel

2. Liquid fuel

iii) Gaseous fuel

( c) State any two qualities of good fuel

14. (a) Define the following terms

1. Green house effect

2. Global warming

3. Acidic rains

4. Pollution

(b)Give any four examples of green house gases

15. (a) Define the following terms:

    1. Fuel ……………………………………………………………………………………………………………………………………………………

    2. Calorific value of a fuel ……………………………………………………………………………………………………………………………………………………

    3. Energy value of a fuel ……………………………………………………………………………………………………………………………………………………

(b) Give two examples of each of the following:

(i) Solid fuel ………………………………….., ……………………………..

(ii) Liquid fuel…………………………………..,……………………………...

(iii) Gaseous fuel ……………………………….., …………………………….

(c) Name four characteristics of a good fuel

(i) ………………………………………………………………………………

(ii) ………………………………………………………………………………

(iii) ……………………………………………………………………………..

(iv) ……………………………………………………………………………..

CHEMISTRY EXAMINATION FORM THREE

TOPICAL EXAMINATIONS.

MOLE CONCEPT

NAME………………………………………..CLASS…………………………………………….……………TIME: 2¹/₂HRS

INSTRUCTIONS:-

1. This paper consists of sections A, B and C

2. Answer all questions

3. All answers must be written in the spaces provided

4. All writings should be in blue/black inks except for drawings that should be in pencils

i) If 0.9g of calcium metal is burnt inair, the mass of powder formed is:

1. 1.14g

2. 1.18g

3. 1.12g

4. 1.26g

ii) If 1g of hydrogen is exploded in air, the mass of water formed is:

1. 1.8g

2. 9g

3. 4g

4. 18g

3. What mass of pure sulphuric acid is found in 400cm3 of its 0.1M?

1. 2.45gm B. 9.80gm C. 3.92gm D. 4.90gm

3. The volume of 18M concentrated sulphuric acid that must be diluted with distilled water to prepare 10 litres of 0.125M sulphuric acid is;

1. 69.44cm³ B. 22500cm³ C. 225cm³ D. 4440cm³

3. If two jars labelled W and Z contain 22.4cm³ of oxygen gas and 22.4dm³ of nitrogen gas at STP respectively, then it is true that;

1. There were 6.02 x 10²³ oxygen molecules in jar W and 6.02 x 10²³ nitrogen molecules in jar Z.

2. 6.02 x 10²³ oxygen atoms were in jar W and 6.02 x 10²³ atoms of nitrogen in jar Z.

3. There were 12.4 x 10²³ molecules of oxygen and nitrogen in the gas jars W and Z.

4. 6.02 x 10²³ molecules of oxygen and nitrogen were in the two jars W and Z.

3. Which of the following statement is true about one mole of CO₂;

1. It is contains Avogadro’s number of molecules.

2. It contains 6.023 x 10²³ molecules at room temperature

3. It contains 44g of carbon and 16g of O₂

4. It contains 12g of carbon and 16g of O₂

3. The loss in mass when 100g of marble is heated to a constant mass is;

1. 200g B. 88g C. 44g D. 22.4g E. 22400g

3. The number of atoms present in 0.025 moles of iron is;

1. 6.02 x 10²³ atoms B. 56 atoms C. 5.6 x 10²³ atoms D. 22.4 x10²³ atoms E. 1.51 x 10²³ atoms

3. How many atoms of zinc are there in 165g of zinc?

1. 1.505 x 10²⁵

2. 1.0997 x 10²²

3. 2.2586 x 10²³

4. 9.63 x 10²⁵

SECTION B

2. 3.5 g of a hydrated salt, MSO_4.XH₂O, was heated to a constant mass of 3.21g of the anhydrous salt. Calculate the value of X. (M= 63.5, S= 32, O = 16, H= 1)

3. With the help of a chemical equation, calculate the volume of carbon (IV) oxide produced when 20g of calcium carbonate is heated at standard temperature and pressure (STP). (Ca= 40, C= 12, O =16,)

4. What would be the volume of the gas produced at 20⁰C and 750mmHg.

Molar gas volume at STP is 22.4 litres)

2. 25.0cm³ of sodium hydroxide solution containing 4.0g/dm³ were required for complete neutralization of 0.18g of a dibasic acid. Calculate the relative molecular mass (RMM) of the acid. (Na=23, H= 1, O=16).

3. (a) How many molar volumes of 132.0g of CO₂ are there at STP?

(b) Determine the number of molecules in 0.25 moles of lead (II) nitrate.

2. (a) What mass in grams of hydrated sodium carbonate (Na₂CO₃ . 10H₂O) in 65cm³ of 0.2M solution?

(b) What volume of carbon dioxide would be evolved at STP when 6.2g of copper (II) carbonate is reacted with sulphuric acid?

2. When excess lead (II) nitrate solution was added to a solution containing sodium chloride, a white precipitate was formed and weighed 5.56g. determine the amount of sodium chloride in the solution. (Bb = 207, Cl = 35.5, Na = 23)

3. 32.5 of IRON (III) chloride was reduced by hydrogen to iron metal. Calculate the volume of hydrogen used to in the reaction at room temperature and pressure. The equation of the reaction is shown below.

2FeCl_{3(s) +} 3H_{2 (g)} → 2Fe_(s) +6HCl _(g)

(Fe = 56, Cl = 35.5, molar gas volume = 24 liters at r.t.p).

7. (a). How many moles of calcium are present in 20g of the metal?

b. determine the grams of magnesium that contains 1.8 × 10²⁴ atoms

c. how many ions are there in 4.6 of Na⁺ ions? (Ca ═ 40, Mg ═ 24, Na ═ 23)

8. Find the mass of 3.0g of calcium carbonate.

1. 150g of Calcium carbonate were reacted with 0.2 moles of hydrochloric acid.

1. Write equation of reaction

2. Calculate amount of calcium carbonate that will remain unreached.

2. 0.7 g of gas × occupies 560 cm³ at s.t.p. determine its relative molecular mass.

Molar gas vol. = 22.4L

3. A certain carbonate aCO₃ reacts with dilute hydrochloric acid according to the equation given below.

ACO_3(s) + 2HCl (aq) → Al_{2aq +} CO _(g) + H₂O _(l)

If 1g of the carbonate reacts completely with 20cm³ of the IM HCl. Calculate the relative atomic mass of G. (C = 12.0, O = 16.0)

4. When a hydrocarbon was completely bunted in oxygen, 4.2g of carbon dioxide has1.71g of water were formed. Determine the empirical formula of late hydrocarbon. ( H= 1.0, C = 12.0 , O = 16.0 )

9. Suppose you have 3.92 g of hydrated ammonium iron (II) sulphate, how many moles of the compound do you have?

(H ═ 1, N ═ 14, Fe ═ 56, S ═ 32, O ═ 16)

10. How many grams are there in 3 moles of water?

11. Determine the number of molecules in:

1. 1.3 dm³ of hydrogen at S.T.P

2. 1.2 dm³ of sulphur (IV) Oxide at R.T.P

(L ═ 6.0 × 10²³, Molar gas volume at S.T.P ═ 22.4 dm³ )

LEARNING HUB.TZ

CHEMISTRY EXAMINATION FORM THREE

TOPICAL EXAMINATIONS.

ELECTROLYSIS

NAME………………………………………..CLASS…………………………………………….……………TIME: 2¹/₂HRS

INSTRUCTIONS:-

1. This paper consists of sections A, B and C

2. Answer all questions

3. All answers must be written in the spaces provided

4. All writings should be in blue/black inks except for drawings that should be in pencils

.

SECTION A. 20 MARKS.

1.MULTIPLE CHOICE QUESTIONS

1. During electrolysis the molten Aluminium oxide, 3 Faradays were needed to deposit one mole of aluminium. The number electrons of aluminium will be :

1. 6.02 x 10²³

2. 1.806 x 10²³

3. 18.06 x 10.²³

4. 180.6 x 10²³

5. 1806 x 10²³

2. If a steady current of 2 amperes were passed through an aqueous solution of iron deposited are the cathode will be:-

1. 54g

2. 56g

3. 0.54g

4. 28g

5. 0.52g

3. The use of electricity to decompose molten sodium chloride into its components elements is an example of:-

1. Electroplating

2. Galvanization

3. Hydrolysis

4. Precipitation

5. Electrolysis

4. What is the meaning of electrolysis?

1. Decomposition of a chemical compound by electricity

2. Breaking up by using electric power

3. Oxidation reduction process

4. Passing electricity through a conductor

4. Which is the correct property of an electrolyte

1. It contains free charge carriers

2. It does not have free ions

3. It can not be decomposed by an electric current

4. It contains mainly undissociated molecules

4. Which of the following is not an electrolyte

1. Aqueous sulphuric acid

2. Solid common salt

3. Molten calcium chloride

4. Alcohol in water

4. When dilute sodium chloride solution is electrolysed using carbon electrodes which substance is collected at the cathode

1. Hydrogen

2. Sodium

3. Chloride

4. Oxygen

4. What are cations?

1. Cathode going ions

2. Anode moving ions

3. Negatively charged ions

4. Unionized particles

4. Which particles will be anions in the electrolysis of aqueous copper sulphate using platinum electrodes?

1. SO₄^2- and OH

2. Cu ²⁺ and H⁺

3. Cu ²⁺ and SO₄ ^2-

4. Platinum

4. What is the name given to quantity of substance deposited by one coulomb of electricity on the electrode?

1. Electrochemical equivalent

2. Chemical equivalent

3. 1 mole of the substance

4. 1 G.M.V at s.t.p.

4. Which one of the following is the application of electrolysis

1. Electroplating

2. Isolation of elements

3. Purification of metals

4. All of the above

4. What is the name of the vessel in which electrolysis process is conducted

1. Voltameter

2. Voltmeter

3. Avometer

4. Beaker

2. Match the items in list A with those from list B by writing the letter of the correct response from List B besides the item number in List A.

LIST A

LIST B

Anode Cathode Electrolyte Electrolysis Electrodes Non- electrolyte Strong electrolyte Weak electrolyte Chemical equivalent Electrolytic reduction

Decomposition of substance in molten or in solution by passage of electric current A reduction process by the use of carbon monoxide or hydrogen Relative concentration of ions in solution. Two poles of carbon or metal dipped in solution allow electrons enter or leave electrolyte Coating metal with a thin coat of another metal by electrolysis Positively charged electrode which electrons enter the external circuit. Decomposition of chemical Substance which will conduct electricity. Hydrogen gas liberated due to the passage of electric current Negative electrode Extraction of most reactive metals Oxygen gas in collected Splits up during electrolysis Faraday constant divide by its valency Atomic mass divide by its valency. Completely dissociate during electrolysis. Partially dissociate during electrolysis. Copper metal is deposited Relative position in electrochemical series. Substance that do not conduct electricity.

2. (a) Define

I) Electrochemical equivalent

2. Chemical equivalent

(b) An electric current was passed in series through solutions of calcium chlorides and copper (ii) sulphate. Carbon electrodes were used in both electrolytes. If 2.5 litres of chlorine gas measured at S.T.P. were produced, what volume of oxygen gas would also be produced? What mass of copper was produced?

2. (a) Explain the meaning of the following terms;

1. Electrolysis

2. Electroplating

(b) State faraday laws of electrolysis.

(c) (i) Write chemical equation for the reaction that take place at each electrode during the electrolysis of dilute sulphuric acid using platinum electrode.

(ii) 19300 coulombs of electricity was passed through a solution of copper (II) nitrate.

Calculate the mass of copper deposited at the cathode.

2. (a) By the help of a well labelled circuit diagram explain the electrolysis of a dilute

solution of sodium chloride using graphitic carbon electrodes.

(b) Is the above electrolysis having special name? If yes explain.

(c) Is there any further reaction at the electrodes if the electrolysis is continued near to

dryness of the electrolyte? Explain your answer.

4. Calculate the mass of magnesium metal that will be produced during the electrolysis of molten magnesium chloride if a current of 1.93A is passed through for 16 minutes and 40 seconds.

2. (a) State faradays 1^st law of electrolysis

(b) What mass of silver and what volume of oxygen (at s.t.p) would be liberated in electrolysis by 9650 coulombs of electricity?

7. I)(a) State the faraday law’s of electrolysis

(b) An element P has relative atomic mass of 88. When current of 0.5A was passed through fused chloride of P for 32 minutes and 10 seconds, 0.44g of P was deposited at cathode;

Calculate the number of faraday required to liberate 1mole of P.

i).Write the formula of P ions

ii).Write the formula of hydroxide of P

2. (a) Distinguish between chemical equivalent and electrochemical equivalent of a

substance.

(b) Describe electrolysis of copper (II) sulphate using graphite electrodes.

Note: Diagram is necessary.

2. I) (a) State Faraday laws of electrolysis.

(b) An element Z has a relative atomic mass of 88. When a current of 0.5 amperes was passed through fused chloride of Z for 32 minutes and 10 seconds 0.44 of Z were deposited at the cathode;

1. Calculate the number of Faradays needed to liberate one mole of Z.

2. Write the formula of the Z ions

3. Write the formula of hydroxide of Z.

2. (a) i. List down three (3) factors affecting the selection of ion discharge at the electrode.

ii. Define the term electrolyte.

(b) A bluish copper sulphate aqueous solution was electrolysed by using copper

electrodes.

1. Write ionic chemical equations for the reactions which occurred at the cathode and anode.

2. Explain what will happen to blue colour of copper sulphate solution as electrolysis continues.

(c) i. Define the term Electroplating.

The following apparatus was used in experiment to electroplate an iron knife with Silver;

The K.Ag(CN)₂ contains Ag⁺, K⁺ and CN ions;

ii. Which electrode is the cathode?

3. Name the process taking place at the anode as either oxidation or reduction.

4. Represent the process at each electrode by the appropriate ionic equation.

5. What happen to the electrolyte?

2. (a) 0.02 moles of electrons were passed through a solution of sodium hydroxide using platinum electrodes.

1. Give the names of the gases evolved to each electrode.

2. Write ionic equations of the reaction taking place at the electrodes.

3. Calculate the number of moles of each gas produced and the volume which each gas would occupy at S.T.P.

(b) What mass of copper will be liberated during electrolysis of copper sulphate solution by a charge of one faraday?

(c) An element X has a relative atomic mass of 88. When a current of 0.5A was passed through the fused chloride of X for 32 minutes 10 seconds, 0.44g of X was deposited at the cathode.

1. Calculate the number of faradays needed to liberate 1 mole of X.

2. Write the formula for X ion.

3. Write the formula for hydroxide of X.

(i) What mass of potassium chloride is needed to prepare 250cm³ of 0.235M solution?

1. 4.38g
2. 9.23g
3. 15.60g
4. 31.3g
5. 1.0g

(ii) Which of the following laboratory equipments can accurately measure volume of a titre that has reacted completely with an a liquid?

1. Pipette
2. Burette
3. Measuring cylinder
4. Beaker

(iii) What will be the molarity of a solution which contains 26.5g of anhydrous sodium carbonate in 5dm³of solution?

1. 0.05 M
2. 0.25 M
3. 5.30 M
4. 0.025 M
5. 0.50 M

What volume of 0.2M H₂SO₄ is required to neutralize completely 25cm3 of 0.05M KOH?

1. 0.656cm³
2. 6.125cm³
3. 3.225cm
4. 3.125cm³

 (v)The mass of sodium hydroxide contained in 25cm³ of 0.1M is .

1.  0.5, 
2. 2.85g
3. 25.0g
4. 0.1g
5. 25g

 (vi) A solution of sodium carbonate was prepared in order to get a 2M solution. 200cm³ of this solution was used in a titration experiment. The number of moles present in 200cm³ of 2M solution used in the titration will be;

1.  4.0 
2. 0.04
3. 0.40
4. 0.045

 (vii) Which indicator is suitably used for the titration of weak acid and a strong base?

1. Methyl orange
2. Phenolphthalein
3. Litmus
4. Bromothymol blue

PART II

2. Given that in the chemistry  national four examination, chemistry practical (2A), the following data were obtained by titrating-0.1M HCl with 5.3g/dm³ of X₂ C0₃ using methyl orange as an indicator. Pipette used was 20cm³

 Questions.

1. Complete the table above
2. Calculate titre mean volume
3. Write a balance chemical reaction between  X₂CO₃ and HCL
4. Calculate molarity of X ₂CO₃
5. Identify and name element X

 3. What do we mean by volumetric analysis? 

4. State the use of each of the following apparatus used in the volumetric analysis:

1. Volumetric flask
2. Burette
3. Pipette
4. Measuring cylinder
5. Weighing balance
6. Dropper.

 5. An experiment was carried out to find the value of X in Na₂CO₃.XH₂ . O.12.4g of Na₂CO₃.XH₂O was dissolved in water to make 0.5dm³ of solution. 25cm³ of this solution was transferred to a conical flask and few drops of methlyorange(MO) was added.The solution in a conical flask was then titrated against 0.25M HCl and 20cm³ of acid were required to reach the end point.

1. write balanced chemical equation for the reaction
2. Calculate concentration of Na2CO3.XH2O in mol/dm3.
3. Calculate the value of X.

 6. 6cm³HCL required 22 cm³Of 0.2 M NaOH for complete neutralization. Calculate the concentration of the acid in moles per time.

7. Solution Q was made by dissolving 2.65g of a X₂CO₃in water and diluting it to 250cm^3. 25 cm³ of P was titrated with 0.25 MHCL solution. The results obtained were tabulated as shown.

1. Calculate the average volume of HCL acid used.
2. Calculate the concentration of solution Q in:

1.  Mol /dm³
2. g/ dm³

8. Calculate the molarities of the following solutions:

1. 10.og of sodium hydroxide, NaOH, in 250cm³ of solution
2. 3.5g of iron (II) Sulphate FeSO₄ in 100 Cm³

 9. Calculate the molarities of the following solutions:

1. 10.0 g sodium hydroxide, NaOH, in 250 Cm³ of solution
2. 3.5g of iron (II) sulphate FeSO_4,  in 100cm³ solution.

 10. Calculate the number of moles in:

1. 20cm³ of 0.1M Nitric (v) acid.
2. 150cm³of 0.5 Sodium carbonate.

 10. (a) Explain the meaning of the following.

1. Titration
2. Molar solution

(b)Given that 5.6g of KOH were dissolved in 1dm³ .25cm³ of this solution ( KOH) were titrated with 25cm³ of hydrochloric acid. Calculate;

(i) Molarity of acid

(ii) Concentrationof KOH 

(iii) Name  suitable indicator for this titration.

 11. (a) Define

1. End point of neutralization
2. Indicator
3. Standard solution
4. Secondary standard solution

(b) A solution of sulphuric acid is made by dissolving 5.2g of its mass containing some impurities to make 1 dm³ of solution.

 If 25cm3 of this solution required exactly 25cm³ of 0.1M NaOH for complete  neutralization during the titration process. Calculate the percentage purity of sulphuric acid. 

 12. Define the following terms:

1. Standard solution
2. End points
3. Titration

13. 190 cm³ of the 0.4M lithium carbonate solution was neutralized by 16.0Cm³ of 1MH₂SO_4. Write an equation for the reaction. 

14. In an experiment, 22.00cm³ of 1.0 NaOH  Was neutralized by  170.0 cm3 of nitric (v) Acid. What is the concentration of nitric (v) acid in mol/ dm³.

15. Calculate the molarities of the following solutions:

1. 25.0g of sodium hydroxide, NaOH in 200cm³ of solution.
2. 3.5 g of iron (II) sulphate, FeSO_4, in 250cm³ of solution.

 16. Calculate the volume of

1. 0.1M  Na,CO₃ solution that neutralizes compeletely 2400cm³ of 0.2M H₂SO₄ Solution.
2. 2M nitric (V) acid required to neutralize 25.00 cm³ of 0.5M NaOH.

 17. Xg of Sodium hydroxide were dissolved in distilled water to make 100cm³  of solution . 50 cm³ of the solution required 50cm³. 2M nitric (V) acid for complete neutralization. Caliculate neutralization. Calculate the mass (x) of Sodium hydroxide dissolved ( Na ═ 23 O ═ 16 H ═ 1)

 18. Calculate the amount of calcium carbonate that would remain in 17.0g of calcium carbonate were reacted with 0.25 Moles of hydrochloric acid. The equation for the equation for the reaction is C_aCO₃(g) + 2HCL(aq) → CaCl_2(aq) + CO_{2 +} H₂O(I) (C ═ 12 O ═ 16 Ca ═ 40).

19. 0.88gcm^-3. Calculate the morality of the ammonia solution.

20. How would you prepare 0.15 L of 0.5 M NaOH,  Starting with 6.0M Solution.

21. How would you prepare 0.75 litre of a 0.5M NaoH Solution, starting with solid sodium hydroxide and water.

22. Calculate the volume of 1M sulphuric (vi) acid need to completely neutralize 100cm³ of sodium hydroxide 0.2M in concentration.

23. The reaction below shows, reaction between calcium hydroxide and nitric (iv) acid.

Ca(OH)_{2(S) +} 2HNO_{3(aq) →} Ca(NO₃)_{2(aq) +} 2H₂O_(l)

 If 20 Cm³ of0.2 M nitric(v) acid was used, calculate the volume of Ca(OH)₂ used, given its morality is 0.1M

 24. 3M  nitric acid reacted with 0.5g copper powder as shown below

CU_{(S) +} 2HNO_{3 (aq) →} Cu (NO₃) _{2 +} H₂O

Given (CU = 63.5)

Calculate the volume of 3M nitric acid that reacted with copper.

 25. Calculate the mass of nitrogen present in 25kg bag of ammonium phosphates (NH₄)₂ HPO_4.

 (N = 14, H= 1, P = 31, O = 16)

 26. When 1.08g of aluminium foil were   in a stream of  chlorine gas, the mass of product formed was 3.47g. calculate the

1. Maximum mass of product formed of chlorine was excess (AL 27, CL = 35.5)
2.  
3. Percentage yield of the product formed.

 27. 15.0 cm³ of ethanoic acid (CH₃COOH) was dissolved in water to make 500cm³ of solution. Calculate the concentration of the solution in moles per litre.

(C= 12.0 H = 10, O = 16.0­) (Density= 1.05g/cm³ of ethanoic acid)

 28. The relative formula mass of a mass of hydrocarbon is 58. Draw and  name two possible structure of the hydrocarbon

29. An alcohol has this composition

H= 13.5%

O₂ = 64.9 %

1. Determine the structure of alcohol if empirical formula and molecular are the same.
2. Draw the structure of alcohol if empirical formula and molecular formula are the same.

 30. 6.84g of aluminum sulphate were dissolved in 150cm³ of water calcululate molar concentration of the sulphate ions in the solution. In of aluminium sulphate is 342).

31. Work out the simplest formula of a  compound. Which has the follows composition

• Magnesium 9.8g
• Sulphur13.0g
• Oxygen26.0g
• Water of crystallization 51.2g

 32. 150g of Calcium carbonate were reacted with 0.2 moles of hydrochloric acid.

1. Write equation of reaction
2. Calculate amount of calcium carbonate that will remain unreached.

33. 0.7 g of gas × occupies 560 cm³ at s.t.p. determine its relative molecular mass.

 Molar gas vol = 22.4L

 34. A certain carbonate aCO₃ reacts with dilute hydrochloric acid according to the equation given below.

ACO_3(s) + 2HCl(aq) → al_{2aq +} CO _(g) + H₂O _(l)

If 1g of the carbonate reacts completely with 20cm³ of the IM HCL.Calculate the relative atomic mass of G. (C = 12.0, O = 16.0)

 35. When a hydrocarbon was completely bunted in oxygen, 4.2g of carbon dioxide has1.71g of water were formed. Determine the empirical formula of late hydrocarbon. ( H= 1.0, C = 12.0 , O = 16.0 )

36. (a) What is titration?

 (b) 25cm³ of impure sulphuric acid contains 5.2g/dm³ reacted with 23cm³ of sodium hydroxide solution made by dissolving 4.0g of NaOH in distilled water to make 1.0dm³ solution 

(c) Calculate the percentage of 

 (i) Purity of the acid and(ii) its impurity 

 (d) Mention two areas of application of volumetric analysis 

 37. 20.0cm³ of a 1.4M, Dibasic acid H₂X solution was titrated against 1.0M NaOH solutionuntil neutralization was complete.

1. Write down the equation for the reaction.
2. Calculate the volume of sodium hydroxide solution used.

LEARNING HUB.TZ

CHEMISTRY EXAMINATION FORM THREE

TOPICAL EXAMINATIONS.

COMPOUNDS OF METALS.

NAME………………………………………..CLASS…………………………………………….……………TIME: 2¹/₂HRS

INSTRUCTIONS:-

1. This paper consists of sections A, B and C

2. Answer all questions

3. All answers must be written in the spaces provided

4. All writings should be in blue/black inks except for drawings that should be in pencils

.

SECTION A. 20 MARKS.

1. MULTIPLE CHOICE QUESTIONS

1. Which of the following properties generally increases down the group?

1. Ionization energy

2. Atomic sixe

3. Electro negativity

4. Sodium and zinc

2. When does a chemist fail to identify a compound between sulphur and

iron?

1. a black solid is formed

2. heat is used to join them up

3. yellow color of sulphur and silvery shinny

4. the resulting mass is greater than the individual mass of the elements

5. any of the above A-D does not take place.

3. Which of the following sets of elements is arranged in order of increas­ing electro negativity.

A. Chlorine, fluorine, nitrogen, oxygen, carbon

B. Fluorine, chlorine, oxygen, nitrogen, carbon

C. Carbon, nitrogen, oxygen, chlorine, fluorine

D. Nitrogen, oxygen, carbon, fluorine, chlorine

E. Fluorine, nitrogen, oxygen, chlorine, carbon

(iv) Which method could be used to separate the products in the following equation?

Pb(NO3₃)_2(aq) + 2KI_(aq) → Pb1_2(s) + 2KNO_3(aq)

Colourless colourless yellow colourless

A. Chromatography B. Crystallisation

C. Distillation D. Filtration
E. Condensation

(v) The metal nitrate which will NOT give a metal oxide on heating is

1. calcium nitrate

2. silver nitrate

3. lead nitrate

4. copper nitrate

5. zinc nitrate

(vi) Which of the following pairs of compounds can be used in preparation of calcium sulphate?

1. Calcium carbonate and sodium sulphate

2. Calcium chloride and ammonium sulphate

3. Calcium hydroxide and barium sulphate

4. Calcium nitrate and lead (II) sulphate

5. Calcium chloride and barium sulphate

(vii) The ionic equation when aqueous ammonium chloride reacts with sodium hydroxide solution is represented as:

1. NH4_(aq) +0H^-_(aq) +0H _(aq) → NH_3(g) + H₂0_(I)

2. Na+(aq) + Cl-(aq) → NaCl (s)

3. H+(aq) + OH(aq) → H2O(l)

4. 2NH4(aq) + 2Cl-(aq) → 2NH3(g) + 2HCl(g)

(viii) Three elements, X, Y and Z, are in the same period of the periodic table. The oxide of X is amphoteric, the oxide of Y is basic and the oxide of Z is acidic. Which of the following shows the elements arranged in order of increasing atomic number?

1. X, Y, Z

2. Y, Z, Y

3. Z, X, Y

4. Y, X, Z

5. X, Z, Y

(ix) The only metal which does not react with dilute hydrochloric acid is:-

1. Magnesium

2. Aluminium

3. Copper

4. Zinc

5. Sodium

(x) Brown ring test is a technique used to test the presence of;

A. Sulphate

B. Nitrate

C. Chloride

D. Potassium salts

2. Match the items in List A with their correspondence responses in List B.

LIST A	LIST B
It nitrate is used in manufacture of antifungal cream. Its carbonate is used in removing water hardness. Its nitrates is used as fertilizers. Its hydroxide is used to make ant - acid tablets. Brown ring test. Its nitrates form black residue when heated. Its hydroxide is used as fuming agent in fire extinguisher. Basic oxide Acidic oxide Yellowish solid produced when sodium burn in excess air.	Ammonium radical Sulphur Carbon Copper Sodium oxide Sodium peroxide Silver Sodium Gold Aluminium Phosphorous pent oxide Aluminum oxide Dinitrogen monoxide Magnesium Germanium Iron (ii) sulphate and sulphuric acid. Argon Potassium zincate Test of carbonate in the laboratory

SECTION B

2. (c) Give reasons for the following:

1. A solution of chlorine in water is acidic.

2. Yellow phosphorus is stored under water.

2. Give an account of the following:

1. Anhydrous copper (II) sulphate becomes coloured when exposed to the air for a long time.

2. Carbon dioxide can be collected by the downward delivery method

3. Concentrated sulphuric acid is not used for drying hydrogen sulphide gas.

4. Sodium metal is kept in paraffin oil.

4. (a) With the aid of chemical equations, explain what will happen when aluminum chloride reacts with water.

(b) A student accidentally broke a beaker containing copper (II) sulphat­e crystals. He decided to separate the blue crystals from the small pieces of glass by first dissolving the mixture and then filtering. What were the next steps?

5. (a) Asubuhi Njema child was sick. When she took her to the hospital, she was prescribed some medicine including a bottle of syrup. The bottle was written: shake before you use. What does this statement signify?

2. (i) What is the first step to take when you want to identify the contents of a given salt containing one anion and one cation?

(ii) In a solution of salt and water, identify a solute and a solvent Justify your answer.

2. Sodium is a solid while chlorine is a gas at room temperature although they are in the same period in the Periodic Table. What is the cause of this difference?

6. (a) Describe the effect of:

1. Strongly heating a piece of marble in a Bunsen burner flame.

2. Moistening the residue from (i) above with water.

2. (i) For what reason is slaked lime added to the soil in gardening?

(ii) Why is concentrated sulphuric acid used as a drying agent?

2. Why is zinc used as a coat for iron and not vice versa?

(d) What will happen when:

1. Yellow flowers are introduced into a gas containing chlorine gas?

2. A burning splint is introduced into a gas jar containing hydrogen gas?

3. A glass rod which was dipped in concentrated hydrochloric acid is introduced into a gas jar containing ammonia gas?

4. Sulphur dioxide gas is bubbled through a yellow acidified potassium dichromate solution?

7. (a) Name the ore commonly used in the extraction of copper metal.

(b) Steps (i) to (iv) below are used during the extraction of copper metal from its ore. Write a balanced chemical equation for each step.

(1) Roasting of the concentrated ore (CuFeS₂ ) in air.

2. Heating the roasted ore with silica in the absence of air.

3. Burning copper sulphide in regulated supply of air.

4. Purification of copper by electrolysis using copper sulphate solution electrolyte, pure copper cathode and impure copper obtained from the extraction anode.

(c) With the help of chemical equations explain what will happen to:

1. An iron earring dropped into a container of copper sulphatesolution.

2. Copper knife dipped into zinc nitrate solution.

3. Copper turnings dropped into a container of dilute hydrochloric acid.

8. (a) Explain briefly the following observations with the help of equations.

i) White anhydrous copper (II) sulphate changes its colour to blue when water is added.

2. Vigorous reaction takes place when a small piece of sodium metal is placed in water.

3. Addition of Zinc metal into a solution of copper (II) sulphate results into decolourization of the solution and deposition of a brown solid substance.

9. (a) Sodium, magnesium, zinc, copper and silver are five metals which appear in this order in the activity series; sodium being the most reactive and silver the least reactive. Which one of these metals is:

1. Likely to tarnish most rapidly when exposed to air?

2. Most likely to be found free in nature?

3. Least likely to react with steam?

2. Two of the metals in 4(a) above are usually extracted by electrolysis of their molten chlorides. Name the two (2) metals and give one reason of using this method.

3. (1) Name the positive and negative electrodes of an electrolytic cell.

2. To which electrode will sodium ions in an aqueous dilute solution of sodium chloride migrate during electrolysis?

3. What other ions will migrate to the electrode stated in 4(c)(ii)?

4. Which ions will be discharged at the electrodes stated in 4(c) (ii)?

10. (a) Chemical reactions can be classified into several types. Study the following reactions and then indicate to which type they belong.

i) Action of heat on lead nitrate

ii) The addition of dilute hydrochloric on silver nitrate

3. Action of heat on calcium carbonate in a closed vessel.

iv) Action of chlorine gas on iron(II) chloride

11. Explain how you can separate a mixture of iodine and copper (II) oxide.

12. List three product formed when copper (II) nitrate is heated strongly in a test tube.

13. Aluminum has atomic number 13.

1. Write down the formula of aluminum chloride.

2. State and explain the observation made when a burning magnesium ribbon is plunged into a gas jar of carbon (IV) oxide.

3. State why water is not a suitable extinguisher of an e the observation made when a burning magnesium ribbon is plunged into a gas jar of carbon (IV) oxide.

4. State why water is not a suitable extinguisher of an electrical fire.

5. State the name given to the reaction in which ethane is converted to ethane.

6. Calculate the volume of 0.09M acid that can be from 1DM³ of 1.2M acid.

7. Explain how you would distinguish between a sulphate using barium choride solutions and silute hydrochloride acid.

8. 15.2g of the oxide of metal X was formed when 10.64g of X reacted with excess oxygen. Dermine the formula of the metal oxide of X . (X = 56, O = 16)

9. Name the products found at the cathode anode when concentrated sodium chloride is electrolytes using carbon electrodes.

11. Some iodine became contained with black copper (II) oxide.

1. Explain how you would separate the mixture.

2. Name the chemical techniques that can be used to separate sodium chloride is electrolyzed using carbon electrodes.

11. Name a substance which decomposes on heating to give two gaseous, other than water vapor.

12. Name the two gaseous above.

13. A compound J React with concentrated sulphuric acid (H₂SO₄) TO GIVE BROWN fumes of a compound K. a solution K in water reacts with copper metal to give a dark brown gas L. Name substances J, K and L.

LEARNING HUB.TZ

CHEMISTRY EXAMINATION FORM THREE

TOPICAL EXAMINATIONS.

EXTRACTION OF METAL

NAME………………………………………..CLASS…………………………………………….……………TIME: 2¹/₂HRS

INSTRUCTIONS:-

1. This paper consists of sections A, B and C

2. Answer all questions

3. All answers must be written in the spaces provided

4. All writings should be in blue/black inks except for drawings that should be in pencils

1.MULTIPLE CHOICE QUESTIONS

1. In the reaction;

2FeCl₂ + Cl₂ 2FeCl₃

Chlorine may be regarded as;

1. A reducing agent

2. An oxidizing agent

3. A catalyst

4. Halogens

ii) The best method to extract iron from its ore is;

1. Reduction using carbon

2. Electrolysis of its solution

3. Roasting of iron ore in air

4. Electrolysis of its molten form

iii) In the blast furnace, iron ore is converted into iron metal, which of the following statements about the blast furnace is not true;

1. The reaction in the blast furnace produces a lot of heat which keeps the iron molten

2. Limestone is reacted with impurities to form slag

3. Coke is reacted to reduce iron oxide to iron metal

4. Coke combines with some impurities in the ore

iv) A less electropositive metal may be extracted by;

1. Ore concentration and electrolytic reduction

2. Ore concentration and chemical reduction

3. Ore concentration and purification

4. Ore concentration, reduction and purification.

v) The reason why carbon is put on the reactivity series of metal is because;

A. Has both metallic and non metallic property

B. They are very electropositive

C. They are reducing agents just like metals

D. They are metallic in nature

vi) which of the following is the most electronegative element?

1. Sodium

2. Sulphur

3. Fluorine

4. Chlorine

vii) the addition of calcium chloride in sodium chloride during the extraction of sodium helps to;

1. Increase the solubility of sodium

2. Lower boiling point of sodium

3. Increase boiling point of sodium chloride

4. Make the solution more soluble.

viii) which of the following is not a method of purifying an ore after extraction?

1. Distillation

2. Oxidation

3. Concentration

4. Electro-refining

ix) the common ore used during the extraction of alluminium?

1. Bauxite

2. Cryolite

3. Feldspar

4. Kaolin

x) The following are the three steps which are followed during the extraction of any metal except one, which one?

A. Ore concentration

B. Ore purification

C. Refining

D. Extraction

2. Matching items questions.

3. (a) (i) Name four important ores of iron.

(ii) What objective is achieved when concentrated ore iron is roasted?

(b) Briefly describe balanced chemical reactions taking place in the blast furnace for the extraction of iron.

3. (a) List down four (4) common stages in the extraction of less reactive metals like zinc and copper.

2. Name the ore commonly used in the extraction of iron metal.

3. The following are series of chemical reactions which occur in the blast furnace during the process of extraction of iron metal.

C_(s) + 02→ CO₃ + heat (1)

CO, +C→2C0 (2)

Fe₂0₃ +3C→2Fe +3C0 (3)

Fe2O3 +CO → Fe +2CO2 (4)

1. Indicate the two reducing agents in the blast furnace.

2. Explain the importance of steps (1) to (3).

3. In this process, a compound L which produces a chemical substance that removes impurities as slag is added. Give the name of the substance.

4. Write the complete chemical reactions that compound L undergoes to form slag.

3. study the chart below and answer the questions that follows

Ore T

StepI Excess sodium hydroxide

solution

Step II

Step III

ElectrolysiStep IV

1. Name the ore labeled T

2. State why the ore is first dissolved in excess sodium hydroxide

3. Write down the formula of the aluminium compound in the solution

4. Name the process that takes place in step II

5. Write down the ionic equation taking place in step IV

6. State why the anode electrode is replaced from time to time

7. Name one compound present in the residue

8. Explain why alloys of aluminum are preferred to aluminum for use in overhead power cables.

3. The diagram below shows the blast furnace used in the extraction of iron. Study it and answer the questions that follows;

mixture of coke limestone and iron Oxide A

Hot air blast

Hot air blast

Slag iron

1. State the use of the following in the process

9. Coke

2. Limestone

3. Hot air blast

b) (i) state one important use of the pipe marked

(ii) Give the uses of slag in the furnace and as a product of the process

3. Sodium is extracted by use of a down cell. Study diagram below and answer the questions that follow;

1. What is a down cell?

2. Name substance X and Y

3. In the extraction of sodium, molten calcium chloride is added to the ore, why is this done?

4. Write equation for the reaction occurring at the;

1. Anode

2. Cathode

5. Sodium is collected at the top most part; explain why this is possible

6. Mention one environmental effect of extraction of sodium

7. Explain the role of steel gauze diaphragm

8. How can we store sodium in laboratory

9. Mention some of the uses of sodium.

8. (a) what is a blast furnace?

b) Name the common ore used in the extraction of iron

c) One of the reducing agents in blast furnace is limestone, explain two roles of limestone

d) What is steel? name two uses of steel

e) is there any environmental impact of extraction of iron?

9. ( a) define the term ore?

b) Name the common chief ores of the following metals;

i) Copper

ii) Iron

3. Aluminium

4. Zinc

c) Give the factors that determine the methods used in extraction of metals

d) Explain why it took so long for chemists to be able to extract aluminum from its ore