enwaecchemistry2010

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THEORY QUESTIONS

WAEC SYLLABUS

1. The electron configuration of carbon atom in its excited state is [₆CI

A. 1s²2²2_px¹2py¹

B. 1s² 2s² 2_px² 2_py⁰

C. ls¹2s² 2_Px¹2_px¹2_px¹

D. Is²2s¹2_px¹2px¹

2. An Important medical use of nuclear radiations is

A. activation analysis.

B. carbon dating,

C. radiotherapy.

D. tissue regeneration.

3. Which of the following elements exhibits the same chemical tries as the atom ³³ X? An element with

A. atomic number 17

B. atomic number 18

C. mass number 35

D. mass number 52

4. Which of the following noble gases has electrode structure similar to that of Nin N3? [¹⁴₇N]

A. ₂He

B. ₁₀Ne

C. ₁₈Ar

D. Kr

5. Which of the following equations represents

A. 23/92U ----> 234/90Th + 1/2He

B. 14/7N + He ----> 17/8O 1/1H

C. 239/92U ----> 239/93Np + 0/-1e

D. 13/7N + 4/2He ----> 16/8 O 1/1H

ANSWERS

6. The energy change which accompanies the addition of a electron to a gascous atom is

A. atomization

B. electron affinity

C. electronegativity

D. ionization

7. Which of the following elements is a d-block clement?

A. Calcium

B. Iron

C. Lithium

D. Silicon

8. Calcium and magnesium belong to the same group in the periodic table because both

A. are metals.

B. form cations.

C. form colourless salts

D. have the same number of valence election

9. Which of the following statements about chlorine and iodine at room temperature is correct.

A. Iron

B. Neon

C. Oxygen

D. Sodium

10. Which of the following statements about chlorine and iodine at room temperature is correct

A. Chlorine is gas and iodine is solid.

B. Chlorine is liquid and iodine is gas

C. Chlorine and iodine are gases.

D. have the same number of valence electrons.

ANSWERS

11. If X is a group III element, its oxide would be represent as

A. X₃O₂

B. X₃O

C. X₂0₃

D. XO₃

12. Which of the following species correctly represents an ion of M with 13 [rptpms and 10 electrons?

A. ₁₀M³⁺

B. ₁₀M^3-

C. ₁₃M³⁺

D. ₁₃M^3-

13. A solid substance with high melting and boiling points is likely to be a/an

A. covalent compound

B. dative covalent compound

C. electrovalent compound.

D. non-metal

14. Which of the following molecules has a linear shape?

A. CH₄

B. CO₂

C. H₂S

D. NH₃

15. Which type of bond is represent by the dotted lines in the following structure?

ANSWERS

16. Which of the following molecules has a triple bond in its structure?

A. CH₄

B. NH₃

C. N₂

D. O₂

17. The bonds in crystalline ammonium chloride are

A. covalent and dative.

B. ionic and covalent.

C. ionic, covalent and dative.

D. ionic, covalent and hydrogen bond.

18. Consider the neutralization reaction represented by the following equation: Na₂C0₃ + 2HNO₃ ----> 2NaN0₃ + H₂0 + CO₂ The stoichiometric ratio of acid to base is

A. 2:2

B. 2:1.

C. 1:2.

D. l:l

19. A solution of sodium trioxocarbonate (IV) contains 10.6g in 250 cm of solution. Calculate the concentration of the solution [Na₂C0₃= 106.0]

A. 0.4 mol dm²

B. 1 .Omol din³

C. 10.6 mol dm³

D. 25.0 mol din³

20. What is the volume occupied by 2 moles of ammonia at s.t.p.

A. 44.8dm^-3

B. 22.4dm^-3

C. 11.2dm^-3

D. 5. 6dm^-3

ANSWERS

A. H₂

B. HCI

C. NH₃

D. N₂

23. A given volume of oxygen diffused through a porous partition in $ seconds. How long would it take the same volume of carbon (IV) oxide to diffuse under the same condition? [C=12.0,O= 100]

A. 5.8 seconds

B. 6.8 seconds

C. 9.4 seconds

D. 11.0 seconds

24. Which of the following gases contains the highest number of atoms at s.t.p. ?

A.6 moles ot neon

B. 3 moles of oxygen

C. 2 moles of chlorine

D. I mole of ethane

25. Given that r is rate and p is density, the expression r a 1 represents

ANSWERS

26 The determination of heat of combustion is carried out with

A. a thermometer.

B. a bomb calorimeter.

C. an evaporating dish.

D. a boiling tube.

27. The minimum amount of energy required for effective collisions between reacting particles is known as

A. activation energy.

B. bond energy.

C. kinetic energy.

D. potential energy.

28. Which of the following oxides is basic?

A. NO₂

B. Al₂0₃

C. S0₂

D. CaO

29. Which of the following equimolar solutions would have the hi conductivity?

A. NH₂NO_3(aq)

B. NaNO_3(aq)

C. Mg(N0₃)_2(aq)

D. Al(N0₃)_3(aq)

30. The following substances are normal salts except

A. Al(NO₃)₃

B. FeSO,

C. Mg(OH)N0₃

D. NaCl.

ANSWERS

31. Which of the following chlorides is insoluble in water?

A. AgCl

B. KC₁

C. NILCl

D. ZnCl₂

32. Which of the following factors would not affect the solubility of a gas?

A. Concentration

B. Nature of solvent

C. Pressure

D. Temperature

33. Consider the equilibrium reaction represented by the following equation:

2S0_2(g) + 0_3(g) <====> 2SO_3(g) DH = 395.1 kjmol¹ Which of the following statements about the equilibrium system is correct?

A. Addition of catalyst changes the equilibrium position.

B. Decrease m pressure increases the yield of S0₃.

C. Decrease in pressure increases the equilibrium concentration of 0₂.

D. Increase in temperature favours the forward reaction

34. The rate of chemical reaction of solids are not affected by

A. catalyst

B. pressure

C. particle size

D. temperature

35. Which of the following statements about the cell notation Mg/Mg²⁺//Cu²⁺/Cu is correct?

A. Copper is the anode.

B. Magnesium is reduced.

C. Magnesium is the anode.

D. The double line represents the electrodes.

ANSWERS

36. Which of the following statement about the electrolysis of CuSO_4(aq) using copper cathode and platinum anode is not correct.

A. Copper is deposited at the cathode.

B. Oxygen is liberated at the anode.

C. it is used for purification of copper

D. The solution becomes acidic.

37. What is the change in oxidation number of manganese in the reaction represented by the following equation? MnO_a(aq) + 8H⁺ + 5 e -------> Mn²⁺_(aq) + 4H₂O₍₁₎

A. +3 to+2

B. + 4 to+2

C. + 5 to + 2

D. + 7 to + 2

38. The quantity of electricity required to discharge 1 mole of univalent ion is

A. 9,600C.

B. 48,250C

C. 96,500C

D. 193,000C.

39. Fats and oils are used as raw materials in the following

A. Point industry

B. Plastic industry.

C. Margarine Industry

D. Cosmetics industry.

40. Which of the following substances is trihydric?

A. Ethanol

B. Glycol

C. Glycerol

D. Phenol

ANSWERS

41. An advantage of detergent over soap is, that detergents

A. Are readily available

B. Are in powdered form.

C. Are non-biodegradable

D. Lather readily with water.

42. The product of fermentation of sugar are

A. carbon (IV) oxide and water

B. ethanol and carbon (IV) oxide.

C. ethanol and water

D. ethanol and enzymes.

43. The IUPAC name of C₂H₃COOC₂H₅ is

A. ethyi thanoate

B. ethylpropanoate.

C. propylethanoate.

D. propylpropanoate.

44. An organic compound contains 40.0% carbon, 6.7% hydrogen and 53.3% oxygen. What is the empirical formula of the compound? [0= 16.0, C= 12.0. H= 1.0]

A.C₂HO

B. CHO

C. CH₂0

D.CH0₂

45. Consider the reaction represented by the following equation:

H₂ H₂

H-C=C H ----> X ---> Y

X and Y respectively are

A. ethene and ethane.

B. ethane and ethene.

C. ethyne and ethene.

D. ethene and propene.