2015 WAEC GCE Chemistry Obj And Theory Answers

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FRIDAY 18TH SEPT 2015
Chemistry 2 (Essay) 8:30am - 10:30am
Chemistry 1 (Obj) 10:30am - 11:30am

_______________.______________

1a )
Hydrocarbon ; This is a
compound consisting
of carbon and hydrogen only
.
1b )
-High temperature
-Presence of catalyst
.
1c )
Oxidation is defined as the loss
of electrons
.
1d )
-The object is placed at the
cathode
-The electrolyte to be used
should contain the
electroplating metal
.
1e )
i)Pent - 2-ene
ii )Butanoic acid
.
1f)
Dalton ' s law of partial pressure
states that the
total pressure of a mixture of a
gases equals to sum of
individual pressure
.
1g )
i)-They have improved
mechanical properties
-They are better in service
ii )-Carbon
-Iron
.
1h )
i)Electrovalent bond
ii )Mettalic bond
iii )Electrovalent bond
.
1i )
i)Isomers are compounds having
the same molecular formular but
different structural
formular
ii )Because it is inert and have a
completely filled
orbitals
.
1j )
Galvanic cells are cells that
convert electrical energy to
chemical energy
.

2ai)
-Number of neutrons : -20, Electron
configuration : - 1s ^ 22s ^22p ^63s ^ 23 p^ 64s ^ 1
-Number of neutrons : -10 , Group : - 7
-Number of neutrons : 10, Electron
configuration : - 1s ^ 22s ^22p ^5 , Group : - 0

ii )
-X is alkali metals
-Y is Halogens
-Z is inert or noble gas

iii )
-High melting point - Conduct electricity in molten form
.
2bi)
This is because of decreasing atomic number
ii )
Relative atomic mass is the mass of an element
in one atom of carbon - 12
iii )
V. D =R . A. M/ 2
V. D =32 / 2
=16
.
4ai)
Allotropy is the existence of a
compound in
two or more physical states

.
ii )
-Diamond is crystalline bond
-Graphite is covalent bond

.
iii )
-Diamond is hard because it
consist of fused
carbon whereas graphite
consists of weak
intermolecular forces
-This is because graphite
consists of mobile
electrons in the crystal lattice

.
4bi )
-Excess of oxygen
-Limited supply of air

.
ii )
C (s )+ O2(g)- > CO 2(g )
2C (s )+O2(g )-> 2 CO (g)

.
iii )
-Carbon(iv )Oxide
-Carbon(ii )oxide

.
4ci)
-Pb (NO 3)2 +2 NaCl-> 2 NaNO 3+
PbCl 2

.
ii ) -Molar mass of PbCl 2=207
+(35 .5 * 2)
=207 + 71 =278 g / mol
2g will produce 1g of PbCl 2
1g will produce 1/ 2 * 5. 56
278 g will produce 1/ 2 * 5. 56
=0 .019

.
3ai)
CH3CH= CHCH# is alkene
CH3COOCH 3 is alkanoate
CH3CH(OH )CH2CH3 is alkanol
CH3(CH2 )2CH3 is alkane

.
ii ) -But -2-ene
-ethyl ethanoate
-Butane
-But - 2-ol

.
iii )CH3(CH2 )2 2bi )
-Ultraviolet light ii )
C 2H 6 Cl 2- > C 2H 5Cl HCl

.
iii )
-C 2H 5Cl Cl 2-> C 2H 4Cl 2 HCl
-C 2H 4Cl 2 Cl 2- > C 2H 3Cl 3 HCl
-C 2H 3Cl 3 Cl 2- > C 2H 2Cl 4 HCl
-C 2H 2Cl 4 Cl 4 Cl 2 -> C 2 HCl5 HCl
-C 2HCl 5 Cl 2- > C 2Cl 6 HCl

.
iv )
Hexachloroethane

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