[WAEC EXPO] Get Chemistry WAEC 2014Answers Here (OBJ, Essay)

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Verified CHEMISTRY OBJ:
1-10: DAAABDADCA
11-20: BABBBDCCAC
21-30: CDABDDACBC
31-40: BBDCCCCDBA
41-50: DCABADBABB

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PLS NOTE THAT ^ MEANS RAISE TO POWER.
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(1ai)
Ionic bond is the bond that exists between metallic
and non-metallic atoms.

(1aii)
I ionic bond,
II ionic and covalent bond +1y2+2x-2*3=0

(1bi)
Na2S2O3, 2+2x-6=0
2x=6-2
X=4/2=2
:. the oxidation number of sulphur in Na2S2O3 is 2

(1b)
Na2S2O3, 2+2x-6=0
2x=6-2
X=4/2=2
:. the oxidation number of sulphur in Na2S2O3 is 2

(1c) Faraday’s first law states that the quantity of
substance deposited or liberated during electrolysis is
directly proportional to the amount of current passing
through the electrolyte at constant temperature an
pressure at a given time i.e Q=it

(1d)
i. SO3
ii.NaO

(1e)
i. Exothermic
ii. Endothermic

(1f)
i. It turns blue litmus paper red
ii. It turns red litmus to red

(1g)Efflorescence are substances when exposed to the
atmosphere, they lose their water of crystalization to
the atmosphere.

(1h)
(i.) It is used in making typewriter ribbon
(ii.) for making shoe polish
(iii.) For making carbon black

(1i)
i. It is used for hardening of oil
ii. It is used in breaking heavy hydrocarbon light
fraction
iii. It is used in producing esters for making soap

(1j)
Recall,
m= MQ/nF,
where m= mass of sliver deposited.
Ag^+ + e^- –> Ag
n=1,
m/M=No of moles = 10920/1*96500
m/M=No of moles = 0.113 moles.

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PLS NOTE THAT ^ MEANS RAISE TO POWER.
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(2ai)
This can be defined as a substance formed when an
element gains or looses election

(2aii)
Isotopes: these are element that exist with the same
at its first election, in the valence shell while
aluminium while aluminium retains two hence
magnesium will become more stable than aluminium.

(2bi)
(I)
12Mg= 1S^22S^22p^63S^2
13AL= 1S^22S^22P^63S^23P^1
(II) This is because the first ionization energy
increases across the period but decreases down the
group

(2bii)
Na2O,MgO, Al2O3

(2c)
(1) Allotropes are atoms that exist in different forms
but have the same physical state
(ii)Diamond and Graphite
(iii)
-Diamond is used for making jeweleries
– Graphite is used for making lead pencil

(2d)
2Nacl+H2SO4 –> Na2SO4+2Hcl
(i)
-The gas turns blue litmus paper to red
-The gas is colourless
(ii)2Nacl+H2SO4–> Na2SO4+2Hcl

(2e)
Molar mass(gmol^-1)=mass/Amount.
Amount in moles= 5.68*10^-3/28.
Amount in moles=2.03*10^-4moles.
Amount in moles=0.000203moles.

(3ai)
coagulation
sedimentation
filteration
disinfection

(3aii.) magnesium ion and calcium ion

(3aiii)
-it wastes soaps
– it causes furring of kettles and boilers

(3aiv)
-crude oil spillage
refuse and sewage

(3bi) water is a polar solvent which is an excellent
solvent for electrovalent substances like NaCl but oil is
non-polar which has little affinity for hydroxyl ion

(3bii)
-as dehydrating agent
-as an acid
-as oxidizing agent

(3ci) oxygen and hydrogen chloride

(3cii.)
I-NaOH
II- because it is soluble in water.

(4ai)
I. Anode is the positive electrode through which
current enters the electrolyte
II. Cathode is te negative electrode through which
current leaves the electrolyte

(4aii)
I. Nacl–> Na+ Cl-
II.
Alcl3–> Al^3+ cl-
Al2O3–>Al^3+ O2-

(4aiii)
This is because the reaction of sodium with water is
very explosive and violent but that of aluminum is not

(4bi) This is because one substance is undergoing
oxidation and another reduction at the same time.

(4bii)
Cr2O7^-5 –> Cr^+2
Cl- –> Cl2.

(4biii)
Cr2O7 + Cl^- + 7H2O –> cl^+
Cr2+ + 14H^+ + Cl2

(4c)
Current(I)=6A
Time(t)=1hr30mins
= (1*3600)+(30*60)
=3600+1800
=5400s
Quantity of Electricity(Q)
=I*t
=6*5400
=32400coulombus
m=MQ/nF
Al^3+ + 3e^- –> AL
n=3
m= 27*32400/3*96500
m=3.02g
Mass of aluminum deposited is 3.02g

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