WAEC Questions and Answers on Chemistry for 2019|Check Mostly Repeated WAEC Examination questions (2ND )

Check Mostly Repeated WAEC Examination questions (2ND )-WAEC Questions and Answers on Chemistry for 2019

Here there are in no particular order…..WAEC Questions and Answers on Chemistry for 2019/2020 and the most likely repeated questions to expect . For the first part of this Chemistry Questions,click here

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WAEC Questions and Answers on Chemistry for 2019-OBJECTIVE

40.     Chemicals that are produced in small quantities and with very high degree of purity are

          (a) bulk chemicals (b) fine chemicals          (c) heavy chemicals (d) light chemicals

41.     How many isotopes has hydrogen?

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          (a) 2 (b) 3 (c) 4 (d) 5   

42.     Which of the following metallic oxides is amphoteric?

(a) Al2O3 (b) Fe2O3 (c) MgO (d) Na2O

43.     The compound that makes palm wine taste sour after exposure to the air for few days is (a) ethanol (b) ethanoic acid (c) methanol (d) methanoic acid

44.     The number of atoms in a compound is called

(a) atomic number (b) avogadro number     (c) empirical formula (d) molecular formula

45.     Flourine is sometimes added in the treatment  of town water to   

(a) improve coagulation (b) kill germs and bacteria (c) make the water tasteful           (d) prevent tooth decay

46.     The pH value of FeCl3 solution is likely to be

(a) 3 (b) 9 (c) 7 (d) 11

47.     When a metallic oxide reacts with both acids and bases, the oxide is said to be         

(a) acidic (b) amphoteric (c) basic              (d) complex

48.     The shape of a graphite is

(a) tetrahedral (b) pyramidal (c) hexagonal (d) octahedral

49.     When a substance changes directly from the gaseous state to the solid state without forming a liquid, the substance is said to

(a) condense (b) evaporate (c) sublime      (d) precipitate

50.     The hydrolysis of NH4Cl gives

(a) an acidic solution (b) an alkaline solution (c) a buffer solution (d) a neutral solution

51.     Noble gas molecules are held together by

(a) van der waals forces (b) hydrogen bonds (c) dative bonds (d) covalent bonds

52.     Which of the following phenomena leads to decrease in volume of liquid in an open container?

(a) Brownian motion (b) diffusion (c) evaporation (d) sublimation

53.     The solution which has pH > 7 is

(a) FeCl3 (b) CuSO4 (c) KNO3(aq) (d) Na2CO3 (aq) 

54.     An aqueous solution of Na2CO3 is

(a) acidic (b) alkaline (c) amphoteric          (d) neutral

55.     The oxidation number of sulphur in Fe2(SO4)3 is

(a) +2 (b) +3 (c) +4 (d) +6

56.     The purity of a solid sample can best be determined by its

(a) boiling point (b) melting point                (c) conductivity (d) solubility       

57.     An element X with electronic configuration 1s22s22p63s2  

(a) X2Y5 (b) X2Y3 (c) XY3 (d) XY2

58.     The basicity of H2SO4 is _________________

59.     CFC means ___________________________

60.     What is the term used to describe an oxide whose aqueous solution turns blue litmus red?

(a) strong electrolyte (b) acid anhydride      (c) amphoteric oxide (d) basic oxide 

61      Which of the following compounds is not a double salt? (a) Zn (oH) NO3 (b) KAl (So4)2    (c) KCr (So4)2 (d) (NH4) Fe (So4)2

62      Which of the following decreases in mass on exposure to air? (a) NaOH (b) Fe (c) FeCl3 (d) Na2Co3.10H2O

63      The laboratory apparatus used in keeping salts is _____________

64.     Fractional distillation of petroleum depends on difference in

(a) molar masses (b) densities (c) rate of diffusion (d) free points

65.     Separating funnel is used for separating of mixture of 

(a) liquids with different boiling points (b) sediments of a liquid (c) liquids with different colours (d) liquids that are immiscible

66.     Which of the following is not a separation technique?

          (a) sieving (b) dissolution (c) filtration        (d) sublimation

67.     The method used to separate the components of iodine and alom is _________

68.     Which of the following represents a noble gas configuration

          (a) 2, 8, 8, 2 (b) 2, 8, 2 (c) 2, 8 (d) 2, 6

69.     What is the family name of group 7 elements is ___________

70.     Na and Na+ have the same

          (a) chemical properties (b) electrical charge (c) electronic configuration (d) number of proton

71.     Which allotrope of carbon is a constituent of a lead pencil?

(a) graphite (b) diamond (c) lampblack (d) soot

72.     The shape of diamond is ____________

73.     The ability of carbon to form multiple bonds with itself to which other atoms are attached is _________

74.     Which of these is not a product of the destructive distillate of coal?

(a) ammoniacal liquor (b) benzere (c) coke (d) coal gas

75.     A given quantity of gas occupies a volume of 228cm3 at a pressure of 750mmHg. What will be its volume at atmospheric pressure?

(a) 200cm3 (b) 225cm3 (c) 230cm3             (d) 235cm3

76.     30dm3 of oxygen of watm is placed in a 20dm3 container. Calculate the new pressure if the temperature is kept constant

          (a) 6.7atm (b) 15.0atm (c) 6.0atm             (d) 66.0atm

77.     Which of the following expressions correctly represents Charles’ law?

          (a) PV = k (b) P &  (c) PV = nkT (d) v = kT

78.     A fixed mass of gas has a volume of 92cm3 at 30c. What will be its volume at 180C, if the pressure remains constant

(a) 90.8cm3 (b) 97.0cm3 (c) 99.3cm3          (d) 151cm3

79.     In the PV = nRT, R represents __________

80.     Which of the following is not a natural constituent of the atmosphere?

(a) water vapour (b) carbon (ii) oxide         (c) nitrogen (d) carbon (iv) oxide

81.     The constituent of air which also acts as a solvent for other constituents is ________

82.     Global warming arises from atmospheric pollution by

          (a) radioactive fallout (b) carbon (iv) oxide (c) agrochemcials (d) sulphur (iv) oxide

83.     The gas that is most useful in protecting humans against solar radiation is

          (a) chlorine (b) ozone (c) carbon (iv) oxide (d) hydrogen sulphide

84.     When a few drops of water is added to blue anhydrous cabalt (iv) chloride, the coloar changes to

          (a) white (b) pink (c) red (d) blue

85.     Which of the following processes is not involved in the treatment of water far town supply?

          (a) chlorination (b) coagulation                         (c) dehydration (d) sedimentation    

86.     Which of the following processes is not involved in the treatment of water far town supply?

          (a) hydrogen sulphide (b) lead compounds (c) metal scraps (d) sewage

87.     The acid responsible for the sour taste of old palm wine is ___________

88.     The acid in the sting of insects and bees is ____________

89.     A base that is soluble in water is called __________

90.     Which of these arrangements is correct for increasing order of PH values of the following salts

(a) KNO3(aq)           NH4cl(aq)                   Na2Co3

(b) Na2CO3(aq)                    NH4cl(aq)                  (c) NH4cl(aq)            KNO3(aq)          Na2CO3(aq) (d) NH4cl(aq)                   KNO3(aq)                Na2CO3

91.     Which of the following pairs of salts would give a solution with a pH of exactly 7?

          (a)CH3 COOK and C6H5 COONa (b) Fecl3 and NH4cl (c) Nacl and Na2SO4 (d) Na2CO3 and NH4cl

92.     The effect of K2CO3 on litmus is that ____________________

93.     Which of the following is the correct dissociation of Na2Co3

(a) Na2Co3           2Na+ + CO32- (b) 2Na2CO3                   2Na++ 2CO32- (c) Na2Co3         Na+ + CO32- (d) Na2Co3          Na2+ + CO32

94.     The chemical formula used to express rust is _____________

95.     Amalgamation is the coating of a metal using ___________ metal

96.     Nitrogen, phosphorus and potassium are the raw materials for the _________ industry

97.     The type of change involved when wood burns to give charcoal is __________ change

98.     The rusting of iron is an example of _______ change

99.     The oxidation number of sulphur in H2S is __________

100.    The raw material for the paint industry is ___

WAEC Questions and Answers on Chemistry for 2019-SECTION B – THEORY

Instruction: Answer Question 1 and Any Other Three. Answer Four Questions in All  

1ai.     What is “Air Pollution”?        (2 Marks)

ii.       List two substances that can cause Air Pollution                       (2 Marks)

bi.      State four reasons why Air is a mixture                                   (4 Marks)

ii.       Mention two salts that are responsible for Permanently Hard Water      (2 Marks)

c.       Mention two Salt Solutions which would:

i.        Turn blue Litmus Red

ii.       Turn red Litmus Blue

iii.       Have no effect on Litmus    (6 Marks)

di.      What is an Acid Anhydride?  (2 Marks)

ii.       Give an example of an Acid Anhydride

                                                (1 Marks)

                                          Total = (19 Marks)

2ai.     What is Salt?                     (2 Marks)

ii.       Mention two types of Salts and give one example of each type mentioned                                             (2 Marks)

iii.       Distinguish between a Strong Acid and a Concentrated Acid                  (2 Marks)

b.       Write an equation to show a Neutralization Reaction                           (1 Marks)

                                                Total = (7 Marks)

3ai.     Define the term “Water of Crystallization”                               (2 Marks)

ii.       Give the names of the compounds below:

  i.        Na2CO3.10H2O         

ii.       CuSO4.5H2O             (1 Mark)

bi.      Define the term “Air”           (2 Marks)

iv.      Mention one air Pollutant     (1 Mark)

c.       Give one difference between Rusting and Burning                    (1 Marks)

                                                Total = (7 Marks)

4a.     List the steps in the treatment of water for township supply                (5 Marks)

b.       Define the term “Hard Water”                                                        (2 Marks)

                                                Total = (7 Marks)

5ai.     What is Solubility?               (2 Marks)

ii.       13.5kg of KNO3 completely dissolved in 50cm3 of Water. Calculate the Solubility of KNO3 in moles for dm3 (K = 39, N = 14, O = 16)                                    (3 Marks)

b.       Mention two methods used in the removal of Permanent Hardness of Water                                           (2 Marks)   

                                                Total = (7 Marks)

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