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

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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?

          (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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