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CHEMISTRY (Objective Questions And Answers)


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THEORY QUESTIONS
WAEC SYLLABUS

WASSCE 2006

Objectives



1. How many orbitals are in the d-sub shell?

A. 1

B. 3

C. 5

D. 7


2. An element X has isotopic masses of 6 and 7. If the relative abundance is 1 to 12.5 respectively, what is the relative atomic mass of X?

A. 6.0

B.6.1

C.6.9

D.7.0


3. An atom 238 X decays by alpha particle emission to give an atom Y. The atomic number and mass number of Y are:.

A. 91 and 234 respectively

B. 91 and 238 respectively

C. 92 and 236 respectively D. 93 and 238 respectively


4. An element with mass number 133 and atomic number 55 has

A. 55 electrons and 55 neutrons

B. 55 electrons and 78 neutrons

C. 78 electrons and 78 neutrons D. 78 electrons and 55 neutrons


5. Which of the following pairs of species contains the same of electrons? [6C, 8O, 10Ne, 11Na, 12Mg, 13AI, 17CI]

A. Mg2+ and AI3+

B. CI- and Ne B.

C. Na+ and Mg

D. C and O2-


ANSWERS

6. An element X has electronic configuration Is2 2s2 2p6 3s2 3p6 4s2 To which group of the periodic table does X belong?

A. I

B.II

C. III

D.IV


7. Which of the following sets of elements is arranged in order of increasing first ionization energies?

A. 11Na, 3Li, 19K, 37Rb

B. 37Rb, 19K, 3Li,

C. 3Li 19K, 11Na, 37Rb

D. 37Rb, 19K, 11Na, 3Li


8. Which of the following electronic configurations represent that of a noble gas?

A. 2,8,8,2

B. 2,8,2

C.2,8.

D.2,6


9. Diamond is a hard substance because its carbon atoms are held by

A. delocalised electrons.

B. strong electrostatic

C. van der waals forces

D. strong directional covalent bonds,


10. The presence of unpaired electrons in an atom of a d- block element accounts for its

A. Ductility

B. Lustre

C. Malleability

D. Paramagnetism


ANSWERS

11. Elements which belong to the same group in the periodic table are characterized by

A. Difference of +1 in the oxidation numbers of successive members

B. Presence of the same number of outermost electrons in the respective atoms

C. Difference of 14 atomic mass units between successive

D. Presence of the same number of electron shells in the respective atoms.


12. What atomic number of elements X and Y are 20 and 17 respectively. Which of the following compounds is likely to be formed by the combination of the two elements?

A. XAY

B.XY2

C. BKY3

D.X2Y


13. What type of bond will be formed between elements P and Q if their electronegativity values are 0.8 and 0.4 respectively?

A. Covalent bond

B. Co-ordinate bond

C. Ionic bond

D. Metallic bond


14. What type of chemical bonding is involved in the formation of NH+4 from a molecule of ammonia and a proton?

A. Covalent bonding

B. Co-ordinate covalent bonding

C. Electrovalent bonding

D. Hydrogen' bonding


15. What is responsible for metallic bonding?

A. Attraction between the delocalized electrons and Fixed positive lattice points (cations)

B. Attraction between positive and negative ions

C. Sharing of electrons between the metal atoms

D. Transfer of electrons from one atom to another


Use the following portion of the periodic table to answer Questions 16 to 18.




ANSWERS

16. Which of the letters indicate elements which exist as diatomic gases?

A. B and G

B. C and F

C. C and A

D A and E


17. Which of the letters represents an alkaline earth metal?

A. F

B. E

C. D

D. C


18. Which of the following pairs of letters denotes elements containing the same number of electrons in their outermost shells?

A. C and D

B. E and F

C. Band G

D. A and B


19. If 1 mole of sodium contains 6 x 1023 atoms, how many atoms are contained in 0.6g of sodium?[Na =23]

A. 1.56 x 1023

B. 1.56x1022

C. 3.6 x 1023

D. 3.6 x 1022


20. If 20cm of distilled water is added to 80 cm of 0.50 mol dnr hydrochloric acid, the new concentration of the acid will be

A. 0.10 mol dm -3

B. 0.20 mol dim-3

C. 0.40 mol dm-3

D. 2.00 mol dm -3


ANSWERS

21. Consider the reaction represented by the equation:

2NaHCO3(s) ---heat---> Na2CO3(s) + CO2(g) + H2O(g)- What volume of carbon (IV) oxide at s.t.p is evolved when 0.5 moles of NaHCO3 heated? [Molar volume = 22.4dm3 at s. t. p]

A. 1.12dm3

B. 2.24dm3

C. 5.6DM3

D. 56.0DM3


22. Which of the following gases will have the lowest rate of diffusion under the same conditions? [N=14, 0=16, CI = 35.5, Ar = 40]

A. Argon

B. Chlorine

C. Nitrogen

D. Oxygen


23. Consider the reaction: H+(aq) + OH(aq) H2O(1)- The energy change taking place in the reaction above is enthalpy of

A. Formation

B. Hydration

C. Neutralization

D. Solution


24. Which of the following processes is an endothermic reaction?

A. Dissolving NH4CI crystals in water

B. Addition of concentrated H2SO4 to water

C. Dissolving NaOH pellets in water

D. Passing SO, gas into water


25. In the energy profile diagram below, which letter represents the activation energy for the reverse — reaction?





A. X

B. Y

C. Z

D. P


ANSWERS

26. Which of the following aqueous solution turns red litmus to blue?

A. NaCI

B. CH2COONa

C. AICI3

D. NH4CI


27. Which of the following methods cannot be used to distinguish between a strong acid and a weak acid?

A. Conductivity measurement

B. Measurement of Ph

C. Action on starch iodide paper.

D.


28. The indicator used in neutralizing CH3 COOH and NaOH. Solution has a Ph range of

A. 3 – 5

B. 7 – 8

C. 8 – 10

D. 10 – 12


29. When aqueous ammonia is added to one of the following solution, a white precipitate which dissolves in excess ammonia is formed. Identify the solution.

A. ZnCI2(aq)

B. Pb(NO3)2(aq)

C. CuSO4(aq)

D. FeSO4(aq).


30. When 50 cm3 of a saturated solution of KNO, at 250 was evaporated to dryness, 10g of dry salt was obtained. What is the solubility of KNO3 at 250C? [KNO3 = 101]

A. 0.10 mol dm-3

B. 2.0 mol dm-3

C. 5.0 mol dm3

D. 10.0 mol dm-3​


ANSWERS

31. Which of the following compounds absorbs moisture from the atmosphere and dissolves in it?

A. FeCI3

B. MgSO4 7H20

C. Na2SO4 D. KCI

D.


32. Consider the diagram below: The set-up is used for the preparation of a salt by





A. double decomposition

B. crystallization

C. neutralization

D. direct combination


33. Consider the equation for the equilibrium reaction.

N2(g) + 3H2(g) <====> 2NH3(g) AH= - 92 kjmol-1 The equilibrium constant for the reaction can be expressed as





34. Consider the reaction represented by the equation:

2S02(g) + 02(g) <=====> 2S03(g) DH = -l97kJmol-' Which of the following conditions will not increase the yield of sulphur (VI)oxide?

A. Increase in temperature

B. Decrease in temperature

C. Increase in pressure

D. Addition of 02 into the mixture


35. Electrolysis is applied in the following processes except

A. electroplating

B. extraction of aluminum

C. extraction of iron

D. purification copper.


ANSWERS

36. The oxidation number of iodine in the iodate ion (10) is

A. -5

B. -l

C. + l

D. +5


37. Metals can be extracted from their ores by a process involving

A. reduction

B. oxidation

C. hydrolysis

D. decomposition


38. Consider the reaction:

2AI(S) + 6H+(aq) 2AI2+(aq} 3H2(g). What is the total number of moles of electrons transferred front the aluminium atoms to the hydrogen ions?

A. 3

B.4

C.5

D.6


39. In the reaction represented by the equation:

5Fe2+ (aq) + Mn04(aq) + 8H+(aq) ------> 5Fe3+ (aq) + Mn2+(aq) + 4H20(I), which species is reduced?

A. Fe2+

B. Mn04-

C. H+

D. Fe3+


Use the structure of the compound below to answer Questions 40 and 41





40. The name of the compound is

A. 2,3-dimethylbutan-l-oI

B. 2,3-dimethylbutan-4-ol.

C. 2-methylbutan-l-ol.

D. 3-methylbutan-l-ol.


ANSWERS

41. The product of the complete oxidation of the compound will be an

A. alkane

B. alkanal

C. alkanoic acid

D. alkanone.


42. Which of the following industrial processes is chlorine not used?

A. Production of polyvinylchloride (PVC)

B. Manufacturing of hydrochloric acid

C. Manufacturing of common salt

D. Manufacturing of domestic bleach


43. What type of reaction occurs between vegetable oil and plant ash extract?

A. Displacement

B. Dehydration

C. Neutralization

D. Saponification.


44. Which of the following compounds is an alkanoate?

A. CH3COOH

B. CH3COOCH3

C. CH3 CH2 OH

D. CH3CH,COOH


45. What is C Ft in the following equation? CaHb + 50, 3C02 + ------> 4H20

A. C3H4

B. C3H6

C. C3 H8

D.C5HI0


ANSWERS

46. Which of the following equations represents a substitution reaction?

A. C4H10(g) + CI2(g) -----> C4 + H9 CI(g) + HCI(g)

B. C2H4(g) + HCI(g) ------> C2 H5 CI(1)

C. C2H2(g) + 2H2(g) ------> C2 H6(g)

D. C3H4(g) + 402(g) ------> 3C02(g) + 2H20(g)


47. Greenhouse effect can be reduced by controlling

A. water evaporation

B. burning of wood and fossil fuel.

C. the use of aerosols

D. the use of artificial fertilizers


48. Waste plastic accumulate in the soil and pollute the environment because plastic materials are

A. insoluble in water

B. non-biodegradable

C. easily affected by heat

D. inflammable


49. Which of the following substances is an ore of iron?

A. Bauxite

B. Cassiterite

C. Haematite

D. Steel


50. The ammonium compound used in the manufacture of dry cell is

A. NH4 N03

B. (NH4)2S04

C. NH4CI

D. (NH4)2C03



WASSCE JUNE 2006 CHEMISTRY OBJECTIVE TEST

ANSWERS

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


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