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CHEMISTRY (Objective Questions And Answers)


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THEORY QUESTIONS
WAEC SYLLABUS

WASSCE 2005

Objectives



1. The electronic configuration of an element X is Is2 2s2 2p6 3s2 3p4. It can be deduced that X

A. belongs to group 6 of the Periodic Table.

B. belongs to period IV of the Periodic Table.

C. has 3 unpaired electrons in its atom.

D. has relative molecular mass of 16.


2. What is the mass number of an element having 20 neutrons, 15 protons and 15 electrons?

A. 15

B. 30

C. 35

D. 50


3. Which of the following sets of elements are arranged in order of decreasing atomic size in the Periodic Table?

A. 6C, 4Be, 7N, 80

B. 4Be, 6C, 7N, 80

C. 8O, 7N, „C, 4Be

D. 7N, 80,6C,4Be


4. Which of the following changes is characteristic of an alpha-particle emission?

A. The nucleus loses two protons and two neutrons

B. A proton combines with an electron giving off heat

C. The nucleus splits into two equal parts

D. Four neutrons are lost.


5. An element X has an atomic number of 16. What is its most likely oxidation state in its binary compounds?

A.-3

B.-2

C.+2

D.+4


ANSWERS

6. Consider the table below:





Which pair of elements are in the same group in the Periodic Table?

A. J and K

B. K and L

C. J and L

D. K and M


7. The type of bonding between calcium and oxygen in calcium oxide is

A. metallic

B. covalent

C. ionic

D. coordinate covalent


8. The properties of four compounds P, Q, R and S are shown in the table below. Which of them is ionic? Compound Electrical Conductance Melting point In the molten state A. P Fairly good 280C B. Q Nil 970C C. R Poor 1580C D. S Fairly good 20150C





9. An element which can exist in two or more forms in the same physical state, exhibits

A. isotopy

B. structural isomerism

C, allotropy

D. variable valency


10. Which of the following can be used to predict the type of bonding in HCI?

A. pH value

B. Electronegativity difference

C. Heat of neutralization D. Heat of solution


ANSWERS

11. Which of the following molecules has a linear structure?

A. NH,

B.H,0

C.CO,

D. CH4


12. The volume occupied by a given mass of gas depends on its

A. diffusion rate

B. temperature and pressure

C. degree of solubility

D. relative density


13. What volume of hydrogen at s.t.p. will be produced when 48g of magnesium reacts completely with dilute hydrochloric acid according to the following equation?

Mg(s) + 2HCI(aq) ----> MgCI2(aq) + H2(g) [Mg = 24, 1 mole of hydrogen occupies 22.4 dm3 at s.t.p.]

A. 11.2 gm3

B. 22.4gm3

C. 33.6gm3

D. 44.8gm3


14. In which of the following reactions is the position of equilibrium not affected by an increase in pressure?

A. 3Fe(s) + 4H2(g) <===> Fe3O4(g) + 4H2(g)

B. 2NO2(g) <===> N2O4(g)

C. 3H2(g) + N2(g) <===> 2NH3(g)

D.2SO(g) + 02(g) <===> 2SO3(g)


15. The activation energy of a reaction can be altered by

A. adding a reducing agent

B. applying a high pressure

C. using a changing the temperature

D.


ANSWERS

16. Which of the following does not affect the rate of reaction of CaCO3 with HCI?

A. Temperature of the reaction

B. surface area of the CaCO3

C. Concentration of the HCI

D. Surface area of the CaCO3


17. When X is heated with manganese (IV) oxide, oxygen is produced. X is

A.KC1

B.KCI03

C.CaC03

D.ZnC03


18. Which of the following statements is not a postulate of the kinetic theory of gases?

A. Molecules move with the same speed

B. lntermolecular forces are negligible

C. Molecules are in a state of constant random motion

D. Collision between molecules is elastic.


19. HN03 does not usually react with metals to liberate hydrogen because HN03 is

A. a strong acid

B. a corrosive acid

C. an oxidizing agent

D. a nitrating agent.


20. Which of the following is not an acid anhyride?

A.P205

B.NO2

C.S02

D.CO


ANSWERS

21. NaHC03(s) can be distinguished from Na,C03(s) by the action of

A. dilute hydrochloric acid

B. carbon (IV) oxide

C. aqueous ammonia

D. heat


22. What process is involved in the reaction represented by the following equation? AICI3(S) + 3H2O(1) ----->Al(OH)3(s) + 3HCI(g)

A. Dehydration

B. Hydrolysis

C. Double decomposition

D. neutralization


23. A salt that absorbs moisture from the atmosphere without forming a solution is said to be

A. efflorescent

B. deliquescent

C. hygroscopic

D. insoluble


24. Consider the reaction represented by the equation below.

xNH3(g) + yCI2(g) zHCI(g) + N2(g) The values of x, y and z are respectively:

A. 2,4,6

B. 3,2,4

C. 2,3,6

D. 3,2,6


25. Which of the following compounds dissolves readily in water?

A.BaS04

B.CuC03

C.NH.CI

D. AgCI


ANSWERS

26. When ice is changing to water, its temperature remains the same because the heat gained is

A. used to separate the molecules

B. lost partially to the atmosphere

C. used to increase the volume of ice

D. less than activation energy.


27. Which of the following methods is suitable for preparing insoluble salts?

A. Thermal decomposition

B. Oxidation

C. Double decomposition

D. Neutralization


28. A solution of sodium hydroxide containing 6.0g in 250cm3 of solution has a concentration of

A. 0.04 mol dm3

B. 0.60 mol dm3

C. 0.96 mol dm3

D. 0.15 mol dm3 [molar mass of NaOH = 40g mol-1]


29. In which of the following reactions is sulphur (IV) oxide acting as an oxidizing agent?

A. 2HN03(aq) + S02(g) -----> H2S04(aq) + 2NO2(g)

B. 2KMn04(aq) +5SO2(g) +2H20(1) ----> K2SO4(aq) MnSO4(aq) + 2H2SO4(aq)

C. FeCI3(aq) + S02(g) + 2H20(1) ----> FeCI2(aq) + H2SO4(aq) 2HCI(E) + H2SO4(aq)

D. 2H2S(g) + S02(g) ----> 2H2O(I) + 3S(s)


30. Which of the following elements will burn in excess oxygen to form a product that is neutral to litmus?

A. Carbon

B. Hydrogen

C. Sulphur

D. Sodium


ANSWERS

31. Which of the following equations represent a redox reaction?

A. Pb(N03)2(aq) + 2HCI(aq) PbCI3(s) + 2HN03(aq)

B. H2S(g) + CI2(g) 2HCI(g) + S(s)

C. AgCI3(aq) + NaCI(aq) AgCI(S) NaNO3(aq)

D. BaCI2(aq) + K2SO4(aq) BaS04(s) + 2KCI(aq)


32. Determine the mass of copper deposited by 4.0 moles of electrons in the reaction represented by the equation below. Cu2+(aq) + 2e- ----> Cu(s)

A. 32

B. 64

C. 128

D. 256


33. The main difference between a primary cell and a secondary cell is that the primary cell

A. is an electrolytic cell but the secondary is not

B. cannot be recharged but the secondary cell can

C. can be recharged but the secondary cell cannot

D. contains electrodes but the secondary cell does not.


34. A solid can be obtained from its saturated solution by

A. filteration

B. crystallization

C. condensation

D. decomposition.


35. What is the reducing agent in the reaction represented by the wing equation?

Fe3+ (aq) + H2S(g) -----> 2Fe2+(aq) + 2H+ (aq) + S(s)

A. Fe3+ (aq)

B. H2S(G)

C. Fe2*(aq)

D.S(S)


ANSWERS

36. Reactioons undergone by compounds with the general formular include

A. addition

B. esterification

C. substitution

D. dehydration


37. What is X in the reaction represented by the equation below?

C10H22 -----> C2H5 + C2H4 + X

A. Propyne

B. Propanol

C. Propene

D. Propane


38. What is the major product formed when C2H5OH reacts with CH3COOH?

A. C2H2COOCH3

B. C2H5COCH3

C. CH3COOC2H2

D. C3H7COOH


39. What is the IUPAC name of the compound with the structure below?





A. 1.2- dibromoethane

B. Methyl dibromoethane

C. Trans - bromoethene

D. 2 - dibromoethane


40. Which of the following substances is a non-reducing sugar?

A. Sucrose

B. Glucose

C. Fructose

D. Maltose


ANSWERS

41. The colour of the solution formed when ethyne reacts with an acdic solution of potassium tetraoxomanganate (Vll) is

A. purple

B. colourless

C. green

D. pink


42. Consider the reaction represented by the equation below:-

CHI4(g) + 202(g) -----> C02(g) +2H20(1) How many moles of carbon (IV) oxide will be produced from 32g of methane? [H = 1,C= 12, 0= 6]

A. 2

B. 3

C. 4

D. 8


43. Fats are classified as

A. hydrocarbons

B. alkanoates.

C. alkanols

D. carbohydrates


44. Ethyne undergoes the following reactions except

A. polymerisation

B. addition

C. substitution

D. esterification


45. Which of the following compounds has the highest percentage of carbon? [H=1,C=12, 0=16]

A. C2H2

B. C2H4

C. C2H4

D. C2H6O


ANSWERS

46. Hardness in water can be removed by adding

A. copper(ll) tetraoxosulphate (IV)

B. sodium trioxocarbonate (IV)

C. sodium chloride

D. alum


47. Which of the following pairs of solutions will produce a precipitate when mixed?

A. Pb(N03)2(aq) and NaCI(aq)

B. MgS04(aq) and HCI(aq)

C. ZNCI2(aq) and NaOH2(aq)

D. aOH(aq) and HN03(aq)


48. The diagram below represents the reaction profile for an exothermic reaction. Which of the following do P, Q and R represent?





A. Activated complex, heat of reaction, activation energy

B. Heat of reaction, activation energy, activated complex

C. Activation energy, heat of reaction, activated complex

D. Activated complex, activation energy,heat of reaction.


49. Which of the following substances is an alloy of lead?

A. Brass

B. Duralumin

C. Stainless steel

D. Soft solder


50. In which of the following process is biotechnology not applied?

A. Manufacture of drugs

B. Treatment of domestic sewage

C. Production of alcoholic beverage

D. Electroplating of metals



WASSCE JUNE 2005 CHEMISTRY OBJECTIVE TEST

ANSWERS

​1. A 2. C 3. B 4. A 5. B 6. C 7.C 8. D 9. C 10. B 11. C 12. B 13. D 14 A 15. C 16. B 17. B 18. A 19. C 20. D 21. D 22. B 23. C 24. C 25. C 26. A 27. C ¬ 28. B 29. D 30. B 31. B 32. C 33. B 34. B 35. B 36. C 37. 38. C 39. A 40. 41. B 42. A 43. B 44. D 45. A 46. B 47. A. 48. D 49. D 50. D.


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