PRESIDENT’S OFFICE, REGIONAL ADMINISTRATION AND LOCAL GOVERNMENT

SECONDARY EXAMINATION SERIES,

MID TERM ONE – MARCH-2024

CHEMISTRY FORM FOUR

Time: 3Hours

Instructions 

1.         This paper consists of sections A, B, and C with a total eleven (11) questions.
2.         Answer all question in the sections A, B and two (2) questions from section C.
3.         Section A carries sixteen (16) marks, section B fifty four (54) marks and section C carries thirty (30) marks.
4.         All writing should be in blue or black pen, except for diagrams that must be drawn in pencil.
5.         Communication devices and any unauthorized materials are not allowed in the examination room.
6.         Write your Examination Number on every page of your answer booklet (s

SECTION A.

Answer all questions in this section. 

1.         For each of the following items  (i-x).Choose the correct answer from given alternatives and writer its letter besides the item number in the answer booklet provided

1.     An increase in temperature of a gas in enclosed system container caused an increase pressure of the gas. This is because it increases the ;

1. Number of gas molecule
2. Combination of gas  molecule
3. Number of collision between gas molecules
4. Average velocity of gas molecules
5. Kinetic energy of gas particles

2.  1.4g of potassium hydroxide is dissolved in water to form 250cm³ of solution. What is the molarity of the solution

1. 0.001M
2. 0.1M
3. 1.4M
4. 5.6M
5. 6.0M

3.                         When methane undergoes substitution reaction with excess chlorine, What is the final product?

1. Chloromethane
2. Dichloromethane
3. Tetrachloroethane
4. Tetrachloromethane
5. Monochloromethane

4.                         Ethanol reaction with ethanoic  acid  to form a group of organic compound called

1. Alkynes
2. Halo-alkanes
3. Esters
4. Alkenes
5. Alkanes

5.   Insoluble salts like Barium Sulphate generally can be obtained in laboratory by;

1. Evaporation of its concentrated solution
2. Crystallization
3. Precipitation
4. Decomposition
5. Displacement

6.                         In a blast fumace carbon monoxide is prepared by passing carbon dioxide over red hot coke. What is the chemical role of carbon dioxide

1. An acceleration
2. An oxidizing agent
3. Reducing agent
4. A catalyst
5. Oxidized

7.    What is the oxidation number of Phosphorus in the following compound? H₃PO₄

1. -5
2. 0
3. ⁺2
4. ⁺5
5. ^-3

8.  Which of the following is not an organic compound?

1. CO
2. C₆H₁₂O₆
3. CH₄
4. CH₃COOH
5. C₂H₅B₁

9.                         A 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. Zink Nitrate

10.   What action should be taken immediately after concentrated Sulphuric acid is spilled on the skin

1. It should be rinsed off with large amount of water
2. It should be neutralized using concentrated NaOH
3. The affected area should be wrapped tightly and shown to a medical health provider
4. It should be neutralized using solid CaCO₃
5. It should be neutralized with concentrated KOH

2.         Match sources of energy in the list A with corresponding description in list B. Write letter of the correct answer beside item number

SECTION B 

54 MARKS

Answer all questions 

3.         (a) Study the following reaction equation N_2(g)+3H_2(g)   H = -46.2KJlmo1^-1

Use le chateliers Principle, suggest how you would use temperature and pressure to obtain the highest production of ammonium in equilibrium 

(b) The formation of methane from hydrogen and carbon monoxide can be represented by:

CO_{(g) +}2H_2g           CH₃OH        DH= 91KJ.........

What mass of hydrogen would cause heat change of 91KJ?

4.         What is the importance of having fume chamber in Chemistry Laboratory

(ii) Why do laboratory doors open outwards?

(b) State the use of following item in first aid 

1.     Cotton wool
2.  Petroleum jelly
3.      Pain killers
4.       Bandage
5.   Razor blade

5.         Define the following terms;

1.     Molecular formula
2.  Empirical formula

(b) You are provided with compound 22.2%Zuric, 11.6% Sulphur, and 22.3%. Oxygen and the rest water of Crystallization. Calculate the molecular formula of the compound if its molecular mass is 283.

6.         16.8g of impure potassium hydroxide was dissolved in distilled water to make 1000mls. 20mls of this solution required 28mls of 0.07M saulphuric acid to react. Calculate :

(a) molarity of KOH

(b) Mass concentration of pure KOH 

7.         (a) The modern periodic law is based modification of Mendeleev periodic law. Explain how the two theories differ from each other.

(b) Comment on the following statement

(i) Lithium has large size than beryllium 

(ii) Sodium is smaller than Potassium 

(c) gives any four ions whose electronic configuration resemble that of Neon.

8.         (a) state faradays maw of electrolysis

Using the law state above, derive mathematical expression of Faradays first law of electrolysis. 

(b) How many moles of electrons will be transferred is Zinc metal is produced by a current of 14.23A. Supplied for 8.0hrs.

SECTION C

30 MARKS

Answer 2 questions from this section.

9.         With aid of balanced chemical equation; explain the process that occurs in blast fumace during extraction of irons.
10.    (a) define the following terms

1.     Functional group
2.  Homologous series
3.      Isomerism

(b) Write down the molecular structure and IUPAC names of the Isomer whose molecular structure is C₄H₁₀

(c) By naming reagent, stating conditions whenever possible using a balanced equation describe how Ethane could be converted into

1.     Ethane
2.  Chloromethane
3.      1,2,- dibromoethane

11.    Dilute Nitric acid is added to a green solid P.A blue solution R is formed and gas I Precipitate Lime with lime water is formed, the blue solution R is evaporated to dryness in a pyres test tube to give black solid M, brown fumes of gas W and colorless gas which relights a glowing splint was formed.

(a) Identify Substance P, R, I, M, W, and S 

(i) Dilute nitric acid and solid P

(ii) Formation of white precipitate with gas I and Lime water.

PRESIDENT OFFICE REGIONAL  ADMINISTRATION AND LOCAL GOVERNMENT

SECONDARY EXAMINATION SERIES 

COMPETENCE BASED  ASSESSMENT

NEW EXAM FORMAT-2023

032/1 CHEMISTRY FORM FOUR 

MID-TERM EXAMS MARCH – 2023 

Time: 3:00 Hours

Instructions

1. This paper consists of section A, B and C with a total of thirteen (13) questions.
2. Answer all questions in this paper
3. Calculators, cellular phones and any unauthorized materials are not allowed in the examination room
4. Write your Examination Number on every page of your answer booklet(s)
5. The following constants may be used

• Atomic masses: H=1, C=12, O=16, N=14, Pb=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)

Answer All Questions

1. For each of items (i) – (x), Choose the correct answer from the alternatives and write its letter beside the item number in answer sheet provided

1. Mango Juice from Bakhresa was written, “Shake well before use” What does this mean?

1. Suspension
2. Solution
3. Solute
4. Emulsion
5. Solvent

2. Ammonia gas is collected by which method among the following

1. Downward Displacement of water
2. Upward delivery
3. Downward delivery
4. Upward Displacement of air
5. The elements are required by adult plant

3. What volume of hydrogen gas will be produced. When 1.3g of Zinc granules react completely with excess Dilute Sulphuric acid at S.T.P?

1. 223cm³
2. 130cm³
3. 440cm³
4. 220cm³
5. 448cm³

4. Which of the following substances should not be kept closely to the open bottle containing Carbon-dioxide

1. Dilute Nitric acid
2. Dilute Hydrochloric acid
3. Sodium hydroxide solution
4. Sodium Nitrate
5. Dilute Suphuric acid

5. When Nitrogen gas is formed covalently how many electrons are shared between nitrogen atom

1. 2
2. 3
3. 6
4. 5
5. 4

6. The reasons why white am hydrogen copper II sulphate tums blue when exposed in Atmosphere is that it

1. Absorbs water vapour
2. Reacts with Oxygen
3. Reacts with carbon dioxide
4. Becomes Dry
5. Release water to the atmosphere

7. Which action should be taken immediately after concentrated sulphuric acid is spilled on the skin

1. It should be rinsed off with large quantities of running water
2. It should be neutralized with concentrated NaOH
3. The affected area should be wrapped tightly and shown to a medical health provider
4. It should be neutralized with solid CaCO₃
5. It should be neutralized with concentrated KOH

8. The following particles forms the nucleus of an atom

1. Proton only
2. Neutron and Electron and neutron
3. Proton and Electron
4. Proton and neutron
5. Neutron and Electrons

9. What should be done if results Obtained from an experiment do not support the hypothesis

1. The results should be left out
2. A new problem should be identified
3. The experiment should be changed
4. Ideas for further testing to find a solution should be given
5. The hypothesis should be accepted

10. Water exists in three forms, solid, liquid and vapour which among the following are examples of liquid form of water?

1. Rain, Snow, hail
2. Dew, Rain, Ice
3. Mist, Steam, Cloud
4. Rain, Hail, Ice
5. Rain, Mist, Dew

2. Match the properties of element in List A with respective elements in List B by writing the letter of correct response besides item number in answer sheet provided

SECTION B (54 Marks)

Answer all questions in this section

3. (a) The modern Periodic table law is based on modification of Mendeleev Periodic law. Explain the two theories differ from each other.

(b) Comment on the following statement

1. Lithium has large size than Beryllium
2. Sodium is smaller than potassium

(c) Give four ions whose electron configuration resembles that of Neon

4. (a) Mr. Mwabashi asked student to prepare all requirements for extraction of sodium metal. Help them describe the use of each of the following

(i) Calcium Chloride (ii)Graphite rod (iii) Steel gauze

(b) Why is sodium collected upward in down cell?

(c) Write electrodes reaction is down cell during extraction of sodium

5. A solution contains 40.3g of substance XOH per liter 250.0cm³ of this solution required 30.0cm³ of 0.3M sulphuric acid for complete neutralization

1. Calculate the number of moles of XOH that reacted
2. Determine the relative atomic mass of X

6. (a) Differentiate alkanes from alkenes

(b) Study the flow chart below and answer questions that follow;

1. Identify A
2. State one Physical Property of B
3. Give a reason why D pollutes the environment
4. Write equation for formation of F
5. Describe an experiment which can be used to distinguish buteno from butanol.

7.  (a)A mass of 1.24g of a divalent metal was deposited when a current of 6A was passed through a solution of metal sulphate for 12minutes. Determine the relative atomic mass of the metal (1F = 96,500C)

(b)State two application of Electrolysis

8.(a) What is an alkali?

(b) Aqueous solution of 2M electronic acid and 2m nitric (v) acid were tested for electronic conductivity. Which solution is a better conductor of electricity? Explain

(c) Explain why it is not advisable to prepare a sample of carbon dioxide using barium carbonate and dilute Sulphuric (VI) acid

SECTION C (30 Marks)

Answer any two questions in this section

9. (a) What is Isomerism?

(b) Using illustration differentiate chain Isomerism from position Isomerism

(c) Alkenes are saturated, why alkenes are unsaturated explain

10. (a)Explain the following terms

1. Reversible reaction
2. Dynamic equilibrium

(b)The industrial Oxidation of sulphur dioxide is summarized as follows

2So_2(g) + O_2(g)  →  2SO_3(g) DH= -94.9 KJ/Mol

What will be the effect of each of the following on production of sulphur Trioxide?

1. Increase in moles of sulphur dioxide
2. Increase in pressure
3. Decrease of temperature
4. Decrease of moles of sulphur dioxide

(c)Briefly explain how each of the following factors affects the rate of a chemical reaction

1. Temperature
2. Pressure
3. Concentration
4. Catalyst
5. Surface area

(d) Give one good reason for the following

1. Fruits ripe faster during summer than during winter
2. Steel wire get rust faster than iron nails

11. (a)Using Iron filling, describe an experiment that can be conducted to show that Oxygen is present in air

(b)Element U has atomic number 12 while element V gas atomic number 16. How do the melting points of elements compare

(c) In haber process, nitrogen reacts with hydrogen according to the following equation;

3H_2(g) + N_2(g) → 2NH_3(g) DH= -92KJ/Mol

9. What would be the effect of adding catalyst to the position of equilibrium

2. Explain why it is not advisable to use a temperature higher than 773K in haber process

THE PRESIDENT’S OFFICE

MINISTRY OF EDUCATION, REGIONAL ADMINISTRATION AND LOCAL GOVERNMENT

COMPETENCE BASED SECONDARY EXAMINATION SERIES

CHEMISTRY MID TERM EXAMINATION

FORM FOUR-MARCH/APRIL-2022

Time: 3Hours

Instructions.

1. This paper consists of section A, B and C with a total of 14 questions
2. Answer all questions in section A and B and ONE (1) question from section C.
3. Section A and C carries 15 marks, while section B 70 marks
4. Cellular phones and any unauthorized materials are not allowed in the examination room.
5. Non programmable calculators may be used.
6. Write your number on every page of your answer booklet.
7. Where necessary the following constants may be used;

Atomic masses; H=1, C=12, N=14,O=16, Na=23, S,=32, Ca =40, Cl =35.5, Cu=64, Zn=65.

Avogadro’s number = 6.02 x 10²³

GMV at s.t.p = 22.4dm³

1 faraday = 96,500 coulombs.

Standard temperature = 273K

Standard pressure = 760mmHg.

1 Litre = 1 dm³ = 1000cm³

 SECTION A (15 Marks)

 Answer All questions in this section.

1. The method of collecting hydrogen chloride gas in a class experiment is known as:

1.              Downward displacement of water
2.               Downward displacement of air
3.               Upward displacement of air
4.              Fountain
5.               Condensation

2. The only metal which does not react with dilute hydrochloric acid is:-

1.              Magnesium
2.               Copper
3.               Zinc
4.              Sodium
5.               calcium

3. Which among the following equations correctly shows the reaction between chlorine gas and water?

1.              C l_2(g) + H₂0₍₁₎→CI_2(g)

B          2C1_2(g) + 2H₂0₍₁₎→ 4C1^-1_(aq) + 0_2(g) + 2H_2(s)

3.               Cl_2(g) + H₂0₍₁₎→HCl + HOCI(aq)
4.              2Cl_2(g) + 2H₂0(_I) →2H0C1 +H_2(g)
5.               2C12(g)+ 3H₂0₀₎ → C1_{2 (.0} + 2H₃0⁺

4. A gas which when exposed to air forms white fumes is likely to be:

1.              Nitrogen
2.               Chlorine
3.               Ammonia
4.              Hydrogen chloride
5.               Sulphur.

v. Which is not true about hydrogen chloride?

1.              It supports combustion
2.               It is a very soluble gas
3.               It forms white fumes with ammonia
4.              It is acidic in nature
5.               When exposed to air forms white fumes

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

A.      Magnesium sulphate 

B.      Sodium chloride

C.       Calcium sulphate 

D.      Magnesium chloride

7. Study the chemical equations below: which can remove temporary and permanent hardness?

a.       Ca(HCO3)2(aq) → CaCO3(g) + H2O(l) + CO2(g)

b.      Ca(HO)2(aq)  + Ca(HCO3)2(aq) → CaCO3(g) + 2H2O(l) 

c.       Ca2+(aq) + CO2-(aq)  → CaCO3(g) 

d.      Ca2+(aq)  + Na2Z(aq) → 2Na+(aq) + CaZ(g)

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

A.       Calcium carbonate 

B.       Calcium chloride 

C.       Sodium carbonate 

D.      Magnesium sulphate 

E.       Calcium hydrogen carbonate 

9. Which of the above equations (vii) removes temporary hardness of water only? 

A.      a and b

B.      b and c 

C.      c and d

D.      d and a.

10. Which set of compounds when in water cause hardness easily removed by boiling addition of Na₂CO₃ or use of ion exchange?

A.      Ca(HCO₃)₂,  Mg(HCO₃)₂

B.      CaCl₂,  MgSO₄

C.       Fe(NO₃), Ca(NO₃)₂

D.      mgCl₂, FeCl₂

2. Match the physical processes represented by arrows (i) - (v) in List A with the corresponding terms in List B by writing the letter of the correct response beside the item number in the answer booklet provided.

3. Figure 1 below represents the laboratory preparation of hydrogen chloride gas.

(a) Name the parts labelled A, B, C and D.

(b) (i) Do you think the gas can be collected over water? Give reasons for your answer.

2.                      Explain the test for the gas.
3.                      What is the function of C?
4.                      Name the method used to collect the gas.
5.                      Write a balanced chemical equation for the reaction taking place during the preparation of hydrogen chloride gas.

(c) Write chemical equations for the reaction between:

(i) Ammonia gas and hydrogen chloride.

(ii) Hydrogen chloride gas and water.

4. Write equation for reaction between

5.                      Chlorine and Magnesium
6.                      Chlorine and phosphorous
7.                      Chlorine and copper
8.                      Chlorine and hydrogen sulphate

5. Explain what happens when a stream of Hydrogen chloride gas is passed over

1.                      Ammonia  gas
2.                      Iron II solution.

6. Study the diagram below and answer the questions that follow

The apparatus above are used to prepare chlorine

1.          State substance

Y

X

P

2.                      What is the use of conc. Sulphuric acid?
3.                      State the use of p.
4.                      Write equation for reaction occurring at the flask.
5.                      How can you show that  test tube used for collection of chlorine is full?
6.                      Name the method of collection
7.                      Give two uses of chlorine
8.                      State  2 compounds of chlorine that pollute the environment.

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

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

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

8.      Define the following terms;

(e)  Soft water 

(f)    Hard water 

(g)  Permanent hardness of water  (h) Temporary hardness of water 

9.      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.

10.   Balance the following equations: 

  (i)Ca + H₃PO₄→ Ca₃(PO₄)₂ + H₂

2.                      Cu + HNO3 → Cu (NO3 )₂ + NO2 +H20
3.                      SnCi₂+FeC1₃→SnC1₄+FeCI

11.     Give the name of the types of reaction represented by each of the following chemical equations.

1.                      C₃H_8(g) +50,₍₀₎→ 3CO2 + 4H₂0₍₁₎
2.                      2Pb (N 0₃),₍,₎→2Pb0₍,₎ + 4NO2 +0_2(g)

(iii)Zn(s)+CuS0_4(aq) —>ZnSO_4(aq) +CU(S)

12.     Complete the following equations and determine the type of chemical reaction involved in each case.

(i) Zn(s)+ H₂SO_4(aq)→

(i) AgN 03_(aq) + NaCl_(aq)→

(iii) N_2(g) + H_2(g) →

THE PRESIDENT’S OFFICE

MINISTRY OF EDUCATION, REGIONAL ADMINISTRATION AND LOCAL GOVERNMENT

SECONDARY EXAMINATION SERIES

CHEMISTRY 1 MID TERM EXAMINATION

FORM FOUR-2021

Time: 3Hours

Instructions.

1.              This paper consists of section A, B and C with a total of 14 questions
2.              Answer all questions in section A and B and ONE (1) question from section C.
3.              Section A and C carries 15 marks, while section B 70 marks
4.              Cellular phones and any unauthorized materials are not allowed in the examination room.
5.              Non programmable calculators may be used.
6.              Write your number on every page of your answer booklet.
7.              Where necessary the following constants may be used;

Atomic masses; H=1, C=12, N=14,O=16, Na=23, S,=32, Ca =40, Cl =35.5, Cu=64, Zn=65.

Avogadro’s number = 6.02 x 10²³

GMV at s.t.p = 22.4dm³

1 faraday = 96,500 coulombs.

Standard temperature = 273K

Standard pressure = 760mmHg.

1 Litre = 1 dm³ = 1000cm³

 SECTION A (20 Marks)

 Answer All questions in this section.

1. For each of the items (i)-(xv), choose the correct answer from among the given alternatives and write its letter beside the item number in the answer booklet provided.

1.          Most salts have comparatively high melting points because they have;

1.          Crystalline structure   
2.          Low pressure
3.          High specific heat
4.          Strong electronic attractions between ions
5.          Strong covalent bond

2. A magnesium atom and a magnesium ion have the same;

1.          Electron configuration
2.          Number of electrons
3.          Chemical properties
4.          Number of protons

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

4. 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

5. If two jars labelled W and Z contain 22.4dm³ 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.

6. Sodium metal is kept in the oil or kerosene because it;

1.          Sinks in oil but floats on water
2.          is very alkaline
3.          Reacts vigorously with water
4.          Forms a protective coat of sodium oxide with oil

7.                      The following is one of the characteristics properties of non – metals;

1.          They are electronegative in nature
2.          They behave as reducing agents
3.          They form cations by gaining electrons
4.          They form anion by loss of electrons

8.                    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

9. 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.

10. 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    B. 0.04     C. 0.40      D. 0.045

1.        Match the responses in list B with the word or phrases in list A by writing a letter of the correct response in the table provided below;

2. (a) Match the items from list A with those in list B.

3. Figure 1 below represents the laboratory preparation of hydrogen chloride gas.

(a) Name the parts labelled A, B, C and D.

(b) (i) Do you think the gas can be collected over water? Give reasons for your answer.

2. Explain the test for the gas.
3. What is the function of C?
4. Name the method used to collect the gas.
5.  Write a balanced chemical equation for the reaction taking place during the preparation of hydrogen chloride gas.

(c) Write chemical equations for the reaction between:

        (i) Ammonia gas and hydrogen chloride.

         (ii) Hydrogen chloride gas and water.

4. (a) 1.4gm of potassium hydroxide is dissolved in water to form 250m³ of solution. What is the 

     molarity of this solution? 

(b) What is the molar concentration of a solution containing 1.75 moles of the solute in 3 

     litres (dm³)? 

5. (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. 

6. (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 Suphuric acid? 

7. You are given the following symbols of metals’ Zn, Na, Cu, Ag, Mg 

1.        State the metal in each case;

1.            Which reacts vigorously with cold water?
2.          Which reacts strongly with steam but not with cold water?
3.        The metal whose carbonate doesn’t decompose on heating.
4.         The metal whose nitrate decomposes leaving a metallic residue.

2.        Write equation for reactions in (a) (i) and (ii).
3.        Arrange the above metals in order of increasing activity.

8. (a) Give the chemical formula for each of the following; 

1.            Potassium carbonate
2.          Sodium nitrate (III)
3.        Iron (III) nitrate
4.         Aluminum oxide

(b) Complete the following equations and balance them. 

1. AgNO_3(s)         heat →
2. ZnCO_3(s)         heat→
3. KOH_(aq) + H₂SO_4(aq)  →
4. CuSO4 . 5H₂O_(s)        heat _→

9. (a) What is meant by Dilution? 

(b) Determine the litres of water that must be added to 30cm³ of 12M HCl to get a solution 

      which is exactly 0.25M. 

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

(b) State two disadvantages of hard water. 

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

11. (a) Define the terms Molecular formula.

(b) Substance X contains 52.2% carbon, 13.0% hydrogen, the rest being oxygen. Calculate the empirical formula of X. 

(c) If the density of X is 23, calculate the Molecular formula of X. 

SECTION C: 15 MARKS

Answer the questions from this section and include the necessary details.

13. (a) (i) With the aid of a well labelled diagram, explain how you can prepare hydrogen gas 

           from the laboratory, using zinc metal and dilute hydrochloric acid. 

     (ii) Write a balanced chemical for the reaction taking place. 

(b) (i) What is observed which hydrogen is passed over red hot copper (II) Oxide? 

     (ii) Write equation for the reaction that takes place in b(i) above.

(c) Which method would you use to prepare big crystals of sodium nitrate in the laboratory? 

     Explain briefly. 

14.      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;

1.        (i) What piece of apparatus should be used to measure out accurately 25cm³ of sodium

     hydroxide solution? 

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

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

2.        (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. 

THE PRESIDENT’S OFFICE

THE MINISTRY OF EDUCATION AND VOCATIONAL TRAINING

MID TERM EXAMINATIONS-MARCH 2020

032                                                                   CHEMISTRY- FORM FOUR

Duration: 2:30 Hours

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.

Atomic masses: C=12                O=16,   H=1, Mg = 24, Na=23, Cl= 35.5, Ca= 40, Cu= 63.5.

Avogadro’s constant = 6.02 x 10²³ particles

Molar volume of gas at S.T.P = 22.4dm³mol ^-1 or 22400cm³ mol ^-1 

SECTION A (15MARKS)

1. .Question (i) – (x) are multiple choice items, choose among the given alternatives and write its letter into the answer sheet provided:-
2. It compound contain 26.7% carbon, 2.2% hydrogen and the rest is oxygen what is its empirical formula?
3. CHO
4. C₂H₂
5. CH₂O
6. CHO₂
7. The solution are mixed in a beaker and the mass of the beaker and contents is recorded at various times after mixing.

The graph shows  the results.

Mass of beaker

And contents

                                                                                     Time 

The two solutions could be:-

1. Aqueous copper (II) sulphate and aqueous ammonia
2. Aqueous sodium carbonate and dilute nitric acid
3. Aqueous potassium hydroxide and aqueous zinc sulphate
4. Aqueous sodium hydroxide and dilute hydro – chloric acid
5. A student does an experiment in which three test – tubes containing hydrochloric acid.

The diagram below show the test- tubes containing the experiments. Which metal is placed in each test – tube?

The question for the reactions is 

2H₂O₂          Mno₂                              2H₂O+O₂

                        _{(aq)                                                                                        (l)          (g)}

• 100 cm3 of hydrogen peroxide is allowed to completely decompose and 120cm³ of oxygen is produced (one mole of a gas occupies 22400cm³ at room temperature and pressure). The concentration of the hydrogen peroxide is :-
• 0.01mol/dm³
• 0.10mol/dm³
• 0.05mol/dm³
• 0.50mol/dm³
• A student was given a sample of a carbonate, M₂Co₃ where M is a metal. He was asked to find the mass of M₂Co_3, the mass of M₂Co₃ and beaker was 7.69g and mass of  beaker was 5.99g from this ,the mass of M₂Co₃ is:-
• 1.71g
• 5.21g
• 7.69g
• 1.70g
• The moles of sodium chloride in 250cm³ of 0.5M sodium chloride are:-
• 0.250Mol
• 0.125Mol
• 2Mol
• 1.25Mol
• Which of the following properties generally increases down the group?
• Ionization energy
• Atomic size
• Electronegativity
• Sodium and zinc 
• Which of the following combination is not likely to form covalent bond?
• Magnesium and oxygen
• Nitrogen and oxygen
• Sulphur and fluorine
• Sodium and zinc
• One mole of water corresponds to:-
• 6.02 x 10²³ atoms of hydrogen and 6.02 x10²³ oxygen atoms 
• 22.4dm³ at 1atom and 25⁰c
• 1g
• 18g
• Neutrons are present in all atoms except
• H
• He
• C 
• Ne 

SECTION B:70  MARKS

Answer ALL questions

1. An industrialist has approached you for information on the distillation of crude oil .What advice would  you offer as regards the followings:-
2. __  Separation of crude oil into fractions
3. __  The main fractions of crude oil
4. __  Uses of fractions of crude oil
5. __  Uses of fractions of crude oil 
6. __ A schematic representation of the industrial process of fractional distillation of crude oil.

(10 marks)

1. (i) Explain the following terms:-
2. Standard solution
3. The end point of a titration
4. 25cm³ of 0.059M sodium hydroxide solution reacted with 23.5cm³ of dibasic acid, H₂C₂O₄. XH₂O containing 3.8gdm^-3. Given that the ionic equation for the reaction is ;

-Calculate;

i)The molar concentration of the acid

ii)The value of x

d) Write down balanced chemical equation for the reaction involved. (C=12,H=1,0=16)

(10 marks)

1. Identify the allotropes S and R
2. Which of the two allotropes is a good conductor of electricity? Explain
3. Explain the following
4. Carbon dioxide is used as refrigerant
5. Carbon dioxide is used as a fire extinguisher                                        (10 marks)
6. (i) A weak base containing a few drops of methylorange indicator was titrated with a strong acid and the curve below was obtained.

                                 14  

                        pH

                                12                 A

                                10

                                8

                                6                                                         B

                                4

                                2

                               0                                            Volume of hydrochloric acid added(cm³⁾                                                                                                                       

1. What will the colour of the indicator at (i) A   (ii) B
2. Explain why the pH value decreases
3. Write down the equations for the reaction, if any, that takes place between dilute hydrochloric acid and each of the following:-
4. Copper(II) (b) Lead(II) (c) Zinc (d) Sodium hydroxide (e) calcium hydrogen carbonate.

(10marks)

1. Write the electronic configuration of the following elements: E,X, L and H.
2.  Which pair of elements from ions by gaining two electrons?
3. Which element is the most reactive metal?
4. Which two element when reacted form a liquid which freezes at 0⁰c and boils at 100⁰c?
5. Give the formulae of the oxide and chlorides of elements A,G,X and W.(10marks)

1. 7.5g of calcium carbonate was placed in a conical flask containing 50cm³ of dilute hydrochloric acid. The flask was kept at constant temperature and the volume of carbondioxide gas evolved was measured at 20minutes intervals.
2. Not all the calcium carbonate was used a during the reaction. The results were recorded in the table below.

1. Write equation for the reaction between which carbonate and hydrochloric acid
2. Plot a graph of volume of carbondioxide (cm³) against time (min)
3. What volumes of carbondioxide  where evolved during the second 20minutes internal? (20-40)
4. Calculate the mass of 11.2cm³ of carbondioxide gas evolved at S.T.P (molar gas volume = 22.4dm³ at S.T.P).
5. Determine the mass of calcium carbonate which had reacted after 20minutes.                                    (Ca = 40, O= 16, C= 12)                                                                                                   (10marks)

1. (a) Explain the changes take place in the solution of concentrated sodium chloride with carbon anode and a mercury cathode.
2. Two electrolytic cells for solutions of sodium chloride with carbon and a mercury cathode and aqueous copper (II) sulphate with inert electrodes were connected in series. A current of 1.5A was passed for 600seconds. The first cell contained aqueous sodium chloride with a little sodium hydroxide had copper electrodes and reddish brown precipitate formed.
3. Why was there as change in the appearance of the electrolyte in the first cell?
4. Why was a small amount of sodium hydroxide added to aqueous sodium chloride in the second cell?
5. Name the reddish brown precipitate formed.
6. Write an ionic equation for the formation of the substance in (iii)?
7. Calculate 
8. The value for the faraday constant
9. The charge on the electrode                                                                   

1.  A hydrocarbon has a molecular mass of 56. On combustion 0.28g of hydrocarbon gave 0.88g of carbon dioxide and 0.36g of water
2. Calculate the empirical formula of the hydrocarbon 
3. Draw a structural formula of the hydrocarbon
4. To which group of hydrocarbons does the compound belong?

11.       The diagram below represents an assembly of the apparatus used to prepare ethene from an alkanol  X.

1. Name the substances labeled X and Z
2. Name substance Y
3. Name the conditions under which ethene is prepared from the alkanol X. 

10.  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)                                            

12. (a) State Le- chatelier’s principle

(b) The industrial preparation of ammonia in the Haber process is represented by the following equation:

N_2(g)  + 3H_2(g)            catalyst           2NH_3(g)                     H= -46.2KJ/mol

Study the equation carefully then answer the questions that follow:

What will happen to the position of equilibrium if: 

1. The temperature of the equilibrium mixture is increased?
2. More Nitrogen gas is added to the equilibrium mixture?
3. 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.

SECTION C: (15 MARKS)

                                                                   Answer ALL questions

 13. a)Explain what is meant by the following terms:

i) A homologous series

ii) Unsaturated hydrocarbons

iii) Isomerism

b) Write and name all possible isomers of C₅H₁₂

c) Write the structures of the following:

i) 2,3-dimethylbutane

ii) 2,3,4-trimethylpent-2-ene

14. Your village is rich in the raw materials for generation biogas: your DDC seeks advice form you as regards:-

• The raw materials.
• The suitability of sitting the biogas plant in the village
• The physical and chemical principle involved
• Economic importance of biogas.