WAEC CHEMISTRY PAST QUESTION (OBJECTIVE QUESTIONS JUNE 2007)

1. When sodium atom forms the ion Na+,

 A. it gains one electron

B. it gains one proton            

C. it achieves a noble gas configuration

D. its atomic number increases.
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2. Which of the following statements about rare gases are correct? I. Their outermost shells are fully filled II. They are generally unreactive III. Their outermost shells are partially filled IV. They have lone pair of electrons in their outermost shell.

A. l and II only

B. II and III only

C. I, II and Ill only

D. I, II, Ill and IV.

3. How many electrons are in the ion F^-? [¹⁹₉F] 

A.8

B.9

C.10

D.19

4. What is the value of x in the foll0wing nuclear reaction equation?

¹¹₅B + ²⁵¹₉₈Cf           ^x₁₀₃Lr + 3¹₀n

A. 241

B. 259

C. 261

D. 265.

5. Which of the following properties is characteristic of the halogens?

A. Ability to accept electrons readily

B. Ability to donate electrons readily

C. Ability to form basic oxides

 D. Formation of coloured compounds.

6. In which of the following atoms is the ionic radius larger than the atomic radius? [₁₁Na, ₁₂Mg, ₁₃A1, ₁₇C1]

A. Aluminium

B. Chlorine

C. Magnesium

D. Sodium.

7. A transition metal would be expected to

A. form oxides with different formulae

B. have strong oxidizing ability

C. have low density

D. have an atomic structure with an incomplete outermost shell.

8. Which of the following properties & atoms generally increases down a group in the periodic table?

A. Electron affinity

B. Electronegativity

C. Ionic radius

D. Ionization energy.

9. Which of the following statements about sodium is not true?

A. Na is smaller in size than Na.

B. Na is smaller in size than Na+

C. Na’ has fewer electrons than Na.

D. The effective nuclear charge in Na+ is greater than in Na.

10. If the difference between  the electronegativities of two elements is large, the type of bond that can be formed between them is

A. covalent

B. dative

C. ionic

D. metallic

11. Which of the following species does not contain a co-ordinate bond?

A.AI₂CI₆

B. CCL₄

C. H₃0⁺

D.NH⁺

12. Which of the following compounds has hydrogen bonds between its molecules?

A. HF

B. HBr

C. HCL

D. HI.

13. 14.8 g of a salt (z) dissolved ii 250 cm3 of distilled water gives a concentration of 0.80 mol/dm3. Calculate the molar mass of the salt (z).

A. 13.5 g/mol

B. 18.5 g/mol

C. 47.4 g/mol

D. 74.0 g/mol.

14. How many atoms are there in one mole of hydrogen gas? [Avogadro’s constant = 6.02 x 1023/ mol]

A. 1.2 x 1023

B. 6.0 x 1O23

C. 1.2 x 1024

D. 6.0 x 1024.

15. What is the percentage composition of oxygen in K₂Cr₂O₇? [K₂Cr₂O₇ = 294; 0 = 16; K = 39; Cr = 52]

A. 14.20%

B. 26.53%

C. 35.37%

D. 38.09%.

16. What is the IUPAC name of the compound represented by the molecular formula NaCIO₄?

A. Sodium tetraoxochlorate (I)

B. Sodium tetraoxochlorate (IV)

C. Sodium tetraoxochlorate (VI)

D. Sodium tetraoxochlorate (VII).

17. When air is successively passed through sodium hydroxide solution, alkaline pyrogallol and then concentrated tetraoxosulphate (VI) acid, its remaining components are

A. oxygen and water vapour

B. oxygen and nitrogen

C. carbon (IV) oxide and noble gases

D. nitrogen and noble gases.

18. Which of the following gases is lighter than air? A. CO₂

B. SO₂

C. HCI

D. NH₃.

19. Which of the following statements is true of the molecules of a gas under ideal conditions? The molecules

A. move at random

B. undergo inelastic collisions

C. attract each other

D. occupy a large volume.

20. In which of the following compound(s) will heat be absorbed on adding water?

I. KNO₃ II. Concentrated H₂S0₄ Ill. NH₄CI

A. I only

B. Ill only

C. I and Ill only

D. II and Ill only.

21. 25 cm3 of.0.80 mol dm3 hydrochloric acid neutralized 20 cm3 of sodium hydroxide solution. What is the concentration of sodium hydroxide in mol/dm3?

NaOH(aq) + HC1(aq)        NaCl(aq) + H₂O(l)

A. 0.08

B. 0.10

C. 0.80

D. 1.00.

22. Consider the reaction represented by the equation: Ca(OH)_2(aq) + C0_2(g)        CaCO_3(s) + H₂0_(l)

In the reaction above, CO₂ acts as

A. an acidic oxide

B. an oxidizing agent

C. a basic oxide

D. a dehydrating agent

23. Which of the following compounds is a basic salt

A. Mg(N0₃)₂

 B. (NH₄)₂S0₄

C. K₄Fe(CN)₆

D. Zn(OH)Cl,

24. What process is illustrated below?

S_(s) + H₂O            S_(aq)

A. Decomposition of a solid

B. Melting of a solid

C. Formation of saturated solution of a solid

D. Sublimation of a solid

25. A solution of a salt X reacts with AgNO₃ solution to give white precipitate which dissolves in excess aqeous ammonia. X contains

A. cl^-

B. Pb²⁺

C. S0²⁺

 D. Zn²⁺

26. Consider the reaction represented by the following equation:

N_{2(g )} + 3H_2(g)         2NH_2(g)    H = — 92 kj/mol . Finely divided iron is used as catalyst in reaction in order to

A. lower the value of H

B. increase the time for attainment of equilibrium

C. shorten the time for attainment of equilibrium

D. decrease the yield of ammonia.

27. Which of the following factors will affect the rate of formation of S(S) in the reaction represented by equation below? S₂O₃^2- _(aq) + 2H⁺ — SO₂+ H₂O_(l) + S_(S)

A. Increase in temperature

B. lncrease the pressure

C. Removal of H20

D. Use of a catalyst

28. In four separate experiments, the same quantity of magnesium ribbon was added to an excess of hydrochloric acid. In which of the experiments will hydrogen be given off most rapidly?

Experiment	Volume of acid (cm3)	Concentration of acid (mol/dm3)
W X Y Z	10 20 30 50	1.0 0.5 2.0 1.0

       A. W

       B. X

 C. Y

 D. Z

29. Which of these cell notations is correct representation of a Daniell cell

A. Zn_(S) / Zn²⁺_(aq) //Cu²⁺_(aq) / CU_(S)

B CU_(S)/ Cu²⁺_(aq) // Zn²⁺_(aq) / Zn_(S)

C Zn²⁺_(aq) / Zn(S)  // Cu²⁺_(aq) / CU_(S)

D. Cu²⁺_(aq) / CU_(S)// Zn_(S) / Zn²⁺_(aq)

30. Which species undergoes reduction in the reaction represented by the equation below?

 ----H₂S_(aq) + 2FeCI_3(aq)        S_(s) + 2HCI_(aq) + 2FeCl_2(aq)

 A. Fe³⁺

B. H₂S

C. Cl^-

D. S.

31. What is the oxidation number of chromium in K₂crO₄?

 A. +1

B. +2

C. +4          CLICK HERE TO UNDERSTAND THE RULES OF OXIDATION NUMBER

D. +6.          

32. What product is formed at the cathode during the electrolysis of concentrated sodium chloride solution using carbon electrodes?

A. Chlorine

B. Hydogen

C. Oxygen

D. Sodium.

33. Which of the following substances is a suitable solvent for perfumes?

A. Benzene

B. Ethanol

C. Turpentine

D. Water.

34. The complete hydrogenation of C6 H6 in the presence of nickel catatlyst at 200°C gives 

A. C₆H₈

B. C₆H₁₀

 C. C₆H₁₂

D. C6H14

35. What is the empirical formula of a hydrocarbon containing 0.08 moles of carbon and 0.32 moles of hydrogen?

A. CH₂

B. CH₃

C. CH₄

D. C₂H_4.

36. Which of the following pairs of substances can be distinguished by use of NaHCO₃ solution?

A. CH₃CH₂OH and HCOOCH₃

B. CH₃CH₂OH end CH₃COOH

C. CH₃COOH and HCOOH

D. CH₃CH₂OH and CH₃OH.

37. Which of the molecules below are geometric isomers?

38. Alkenes undergo the following reactions except

A. addition

B. hydration

C. polymerization

D. substitution.

39. Hydrocarbons which react with ammoniacal copper (I) chloride solution conform to the general molecular formula

A. C_nH_n

B. C_nH_2n

C. C_nH_2n+2

D. C_nH_2n-2

40. Consider the reaction below:     Vegetable oil   +   H2 Ni catalyst   =    product

                                                                                      High temp.                                                                                                                                                

The reaction is applied in the manufacture of 

        A.  drugs

              B.      margarine

              C.     paraffin wax

              D.     soapy detergents

41. What is the product of the reaction between ethanol and excess acidified

 KMnO₄ solution?

A. CH₂=CH₂

B. CH₃COOH

C. CH₃-CH₃

D. CH₃OCH₃.

42. Which of the following compounds reacts readily with sodium to liberate hydrogen?

A. CH₃CH₂CH₃

B. CH₃COCH₃

C. CH₃CH(OH)CH₃

D. CH₃CH₂CHO.

43. Glucose reduces Fehling’s solution on warming to

A. copper (I) oxide

B. copper (II) oxide

C. copper (I) chloride

D. copper (II) hydroxide.

44. Which of the following activities is not a source of air pollution?

A. Cigarette smoking

B. Carbon dating

C. Domestic fires

D. Coal powered stations.

45. From which of the following ores is iron extracted? I. Haematite II. Bauxite Ill. Magnetite IV. Cassiterite

A. I and II only

B. I and Ill only

C. I, II and lii only

D. I, II, Ill and IV.

46. Which of the following methods can be used to separate a mixture of two miscible liquids with different boiling points?

A. Decantation

B. Distillation

C. Evaporation

D. Filtration.

47. The following substances are heavy chemicals except

A. sodium trioxocarbonate (IV)

B. tetraoxosulpfiate (VI) acid

C. lead (IV) tetraethyl

D. sodium hydroxide.

48. Pig-iron is brittle because it contains

A. a high percentage of carbon as impurity

B. calcium trioxosilicate (IV)

C. unreacted haematite

D. undecomposed limestone.

49. Which of these metals will not liberate hydrogen from dilute HCI?

A. Copper

B. Iron

C. Magnesium

D. Zinc.

50. What volume will 0.5 g of H2 occupy at s.t.p.? [H = 1; 1 mole of a gas occupy 22.4 dm3 at s.t.p.

A. 2.24dm3

B. 5.60dm3

C. 11.20dm3

D. 44.80dm3.

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