CHEMISTRY EXAMINATION QUESTIONS|FIRST TERM EXAMINATION, 2018/2019 SESSION

CHEMISTRY EXAMINATION QUESTIONS|FIRST TERM EXAMINATION, 2018/2019 SESSION

FIRST TERM EXAMINATION, 2018/2019 SESSION 

CLASS: SS 3       SUBJECT:  CHEMISTRY      TIME: 2 HOURS

SECTION A – OBJECTIVES [50MARKS]

Instructions: Answer all questions

1. The atoms of four elements are represented as ₂₀Q, ₁₆R, ₁₀S and ₈ which of the elements would be unreactive A. Q  B. R  C. S  D. T
2. The type of chemical bond that exists between potassium and oxygen in potassium oxide is A. Ionic Metallic C. Covalent   D. Dative
3. Chlorine atom forms Cl^– by A. Losing one electron Sharing one electron  C. Donating one pair of electrons   D. Gaining one electron
4. An element Z has a combining power of 3. Which of the following formulae is correct of its compound A. ZSO₃ Z₃Cl₂  C. Z₂O₃  D. ZS₃
5. The gas evolved when dilute tetraoxosulphate(iv) acid reacts with sodium hydrogentrioxocarbonate(iv) is A. Hydrogen Oxygen
6. Carbon(iv)oxide D. Sulphur(vi)oxide
7. If a solution has a p^H of 2, it can be concluded that it A. Is a weak electrolyte has hydrogen concentration of 0.2moldm^-3 C. Is twice as acidic as a solution of p^H,  D. Will produce effervescence with magnesium ribbon
8. Chemical equilibrium is attained when A. Reactants in the system are used up B. Concentrations of the products are greater than those of the reactants  Concentrations of the reactants and products remain constant  D. reactants stop forming the products
9. An iron nail placed in a solution of copper(ii)tetraoxosulphate(vi) is soon covered with a deposit of copper. Which of the following equations represents the reaction?
10. Fe²⁺_(aq) + Cu(s)   Fe³⁺_(aq)
11. Fe²⁺_(aq) + Cu_(s)      Fe_(s) + Cu²⁺_(aq)
12. Fe_(s) + Cu²⁺_(aq)       Fe²⁺_(aq) + Cu²⁺_(aq)
13. Fe_(s) + Cu²⁺_(aq) Fe²⁺_(aq)
14. Which of the following non-metals reacts most readily with metals? A. Nitrogen Chlorine  C. Sulphur  D. Carbon
15. A radioactive substance is best stored Under paraffin oil  B. Under ultravidet light  C. In a cool, dark cupboard  D. In a box lined with lead

• In the electrolytic extraction of aluminum from puried alumina; molten cryolite is added in order to A. lower the melting point of the alumina

13. Prevent the aerial oxidation of the molten aluminum C. Lower the activation energy of the reaction D. Form a protective  crust on top of the electrolyte
15. When iron rusts, it undergoes A. Deliquescence Chemical decomposition  C. Hydrolysis  D. Redox reaction
16. Which of the following involves the decomposition of a sugar by enzymic action? A. Esterification Fermentation  C. Dehydration
17. Polymerization
18. If a reaction is said to be exothermic, which of the following statements is a correct deduction from the information? The reaction vessel gets hotter as the reaction proceeds  B.  for the reaction is positive  C. The rate of the reaction increases with time  D. The activation energy of the reaction is high
19. A dye s suspected to have contaminated a lollipop. Which of the following is the best method by which the contaminant may be isolated?
20. Fractional distillation B. Recrystallization C. Filtration  D. Paper Chromatography
21. Which of the following accounts for the difference in the mode of conduction of electricity by metals and aqueous salt solutions?
22. Electrons are present in metals but not in salt solutions B. Metals are conducted while salts are electrolytes C. Electricity is carried by mobile electrons in metals but by ions in aqueous  salt solution  D. Salts ionize in aqueous solutions while metals do not.
23. A positive brown ring test indicates the presence of A. NO^–_3­ Fe³⁺
24. D. Cu⁺
25. The following statements about graphite are correct EXCEPT that it A. Is used as a lubricant Has a network structure  C. Contains  mobile free electrons  D. Is a good conductor
26. Which of the following hydrocarbons is unsaturated? A. Ethane
27. Benzene C. Propane D. Z-methylbutane
28. Which of the following is an alloy of mercury? A. Stainless steel Soft solder  C. Coinage bronze  D. Amalgam
29. Metals which react with steam only when they are red-hot include
30. Copper B. Sodium C. Calcium  D. Iron
31. An arrangement of two different metals in aqueous solutions of their salts to produce an electric current is known as A. Electrochemical cell Activity series  C. Thermocouple   D. Volmeter
32. Which of the following exhibits resonance? A. Benzene Butane
33. Pentene D. Octane
34. Which of the following metals will be the most suitable for use where lightness and resistance to corrosion are of important? A. Lead
35. Copper C. Iron D. Aluminum
36. What is the most probable group of an element which is a soft, silvery-white solid and reacts violently with water? A. Group O  Group 1
37. Group 4 D. Group 6
38. Which of the following ions will migrate to the cathode during electrolysis? Zinc ions  B. Chloride ions   C. Suphide ions
39. Tetraoxosulphate(vi)ions
40. Which of the following radioactive decays involve an emission?
41. B. C.
43. The following oxides react with both acids and bases to form salts except A. Zinc oxide Lead (ii) oxide  C. Aluminium oxide   D. Carbon(iv)oxide
44. Which of the following metals is NOT extracted by electrolysis? A. Iron  Sodium  C. Calcium  D. Magnesium
45. Which of the following is an ore of aluminum? A. Haematite
46. Magnetite C. Siderite D. Bauxite
47. Which of the following statements is/are correct about metals? They I. Are good conductors of electricity II. Have mobile electrons III are reducing agent IV. Form acidic oxides I and II only  B. I, II and III only  C. I, II, III and IV   D. None of the above.
48. The main type of reaction that occurs in the blast furnace during the extraction of Iron is A. reduction reaction Decomposition
49. Exothermic reaction D. Combustion
50. Which of the following compounds can be represented by the molecule formula C₂H₆O A. Propanal Ethanol  C. Methanoic acid   D. Glucose
51. The following compounds are hydrocarbons EXCEPT
52. Methylpropanoate B. Z-methylbutane C. Benzene  D. Cyclohexane

36. When alkynes are hydrogenated completely, they produce compounds with the general molecular formula C_nH_n   B. C_nH_2n+2   C. C_nH_2n
37. C_nH_2n-2
38. Which of the following alloys does not contain copper? I. Brass Bronze  III. Steel  A. I only  B. II only  C. III only  D. II and III only
39. The major product in the solvay process is A. NaOH Na₂CO₃  C. NH₃  D. H₂SO₄
40. 100g of radioactive mass has a half-life of 5 days. Calculate the mass decayed off after 15 days. A. 25g 50g   C. 12.5g  D. 6.25g
41. A solution of sodium trioxocarbonate(iv) contains 10.6g in 250cm³ of solution. Calculate the concentration of the solution. A. 0.4moldm^-3
42. 1.0moldm^-3 C. 10.6moldm^-3 D. 25.0moldm^-3
43. The rate of chemical reaction of solids are not affected by A. Catalyst
44. pressure C. Particle size  D. Temperature
45. The energy change that accompanies the addition of an electron to an isolated gaseous atom is A. Bond energy electronegativity  C. electron affinity  D. Ionization energy
46. Which of the following metals could be used as sacrificial anode for preventing the corrosion of iron? A. Copper Lead  C. Magnesium
47. Silver
48. What mass of copper would be formed when a current of 10.0A is passed through a solution of CuSO₄ for 1hour? A. 5.9_g 11.8_g   C. 23.7_g
49. 47.3_g­
50. The volume occupied by 0.4_­­g of hydrogen gas at t.p is A.2.2dm³
51. 4.48dm³ C. 22.4dm³ D. 44.8dm³
52. The oxidation number of Fe in [Fe(CN)₆]^3- is A. +3 +2  C. -2 D. -3
53. Which of the following substances is mainly responsible for the depletion of the ozone layer? A. Oxygen Chlorofluorocarbon  C. Carbon(ii)oxide  D. Nitrogen(ii)oxide
54. Which of the following reactions is common to all hydrocarbons?
55. Combustion B. Addition C. Polymerization  D. Condensation
56. A hydrocarbon compound contains 92.3% carbon. Determine its empirical formula A. CH CH₂  C. CH₃ D. C₂H₃
57. Reduction is the process of A. Loss of electron Loss of hydrogen
58. loss of oxygen D. Addition of electronegative elements

SECTION B – THEORY

Instruction: This section is divided into two parts, answer only two questions from each part.

PART I [ 50 MARKS]

1.(a)   What are nucleons?

(b)   State Graham’s law of diffusion

(c)   Explain briefly why aluminum does not corrode easily

(d)   State THREE examples of periodic properties and their variations in the periodic  table of elements

(e)   State TWO reasons why real gases deviate from ideal gas behave iour

(f)    List THREE uses of fractional distillation in industry

(g)   What factors determine the selective discharge of ions at the electrodes during electrolysis?

(h)  Consider the reaction represented by the following equation

Na₂CO_3(aq) + M_gCl₂           2NaCl_(aq) + M_gCO_3(aq)­

2a.     Consider the following atoms

1. State the phenomenon exhibited by the two atoms
2. What is the difference between the atoms?

iii.    Give two examples of elements that exhibit the phenomenon stated in   2(a)(i)

iv     If T is 17, write the electron configuration of the element

b(i)     State two differences between metals and non-metals with respect to their: I. Physical properties              (ii) Chemical properties

b (ii)   Give one example of each of the following compounds

• An amphoteric oxide
• A hydride which evolves hydrogen when reacted with water;
• A trioxocarbonate(iv) salt which is readily decomposed on heating
• A chloride salt which is readily hydrolyzed in water

c(i)     State THREE characteristic properties of transition metals

(ii)      Write the electro configuration of ₃₀Zn

(iii)     Explain briefly why zinc is not considered as a typical transition element

3(ai)   State Graham’s Law of diffusion

(aii)  If 100cm³ of oxygen diffused in 4seconds and 50cm³ of gas Y diffused in 3 seconds, Calculate the relative molecular mass of gas Y

(b)      Consider the following equilibrium reaction:

X_(g)+2Y_(g                 XY_2(g)­  = -52KJmol^-1

1. i) State what happens to the yield of XY₂ when the temperature is increased

(ii)      Explain the effect of decrease in pressure on the equilibrium position

(iii)     State the effect of a catalyst on the

1. Position of equilibrium
2. Activation energy

c.(i)    State two differences between the solubilities of solids and gases in liquids

c.(ii)   Name the physical  properties used in choosing separation techniques for the following mixtures I. Kerosene and Petrol II. Calcium trioxocarbonate (iv) and potassium chloride III. Ammonium chloride and sodium chloride

d(i)     State a method of preparing each of the following salts;

1. Sodium Chloride
2. Lead (II) Trioxocarbonate (iv)

• Iron (ii) Chloride

1. Copy and complete the table below

Acid                      Basicity

H₃PO₄

CH₃COOH

HNO₃

D(i)    State the difference between analydrous and hydrated salts

PART II [50 MARKS]

4a.     What is the main source of aluminium in nature?

1. Using a diagram and equations, explain how pure aluminium is extracted from the above source
2. The common radioactive isotope of radium – 226 has a half-life of 1620 years. Calculate:
3. The first order rate constant for the decay of radium – 226
4. The fraction of a sample which remains after 100years.

5a.     Using diagrams and equations, explain how iron is extracted from its ores.

1. What is the chemical nature of iron rust? How would you attempt to determine by a series of chemical reactions that iron rust contains iron?
2. Write short notes on the following (i) cast iron (ii) wrong iron (iii) pig iron  (iv) steel

3a(i)   What is a solution?

(ii)   Why is water regarded as a universal solvent?

6. Ethane burns completely in oxygen; what is the amount in moles of carbon (iv) oxide that will be produced when 6.0g of ethane are completely burnt in oxygen?
7. A solution of trioxonitrate(v) acid contained 0.67g in 100cm³ 31cm³ of this solution neutralized 25cm³ of a sodium trioxocarbonate(iv) solution. Calculate the concentration of the trioxocarbonate (iv) solution
   

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