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100% Real Waec Gce 2015 Chemistry Obj And Theory Answers.


CHEMISTRY OBJ:
1-10: AABABACACA
11-20: DABAAACDDB
21-30: ADDCCDCDCC
31-40: AACCADCDAB
41-50: ADDCCBAACD

(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^23p^64s^1
-Number of neutrons:-10,Group:-7
-Number of neutrons:10,Electron
configuration:-1s^22s^22p^5,Group:-0
(2aii)
-X is alkali metals
-Y is Halogens
-Z is inert or noble gas
(2aiii)
-High melting point
-Conduct electricity in molten form
(2bi)
This is because of decreasing atomic number
(2bii)
Relative atomic mass is the mass of an
element in
one atom of carbon-12
(2biii)
V.D=R.A.M/2
V.D=32/2
=16
(3ai)
CH3CH=CHCH# is alkene
CH3COOCH3 is alkanoate
CH3CH(OH)CH2CH3 is alkanol
CH3(CH2)2CH3 is alkane
(3aii)
-But-2-ene
-ethyl ethanoate
-Butane
-But-2-ol
(3aiii)
CH3(CH2)2C2H5Cl+HCl
(3biii)
-C2H5Cl+Cl2->C2H4Cl2+HCl
-C2H4Cl2+Cl2->C2H3Cl3+HCl
-C2H3Cl3+Cl2->C2H2Cl4+HCl
-C2H2Cl4+Cl4+Cl2->C2HCl5+HCl
-C2HCl5+Cl2->C2Cl6+HCl
(3biv)
Hexachloroethane
(4ai)
Allotropy is the existence of a compound in
two
or more physical states
(4aii)
-Diamond is crystalline bond
-Graphite is covalent bond
(4aiii)
-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
(4bii)
C(s)+O2(g)->CO2(g)
2C(s)+O2(g)->2CO(g)
(4biii)
-Carbon(iv)Oxide
-Carbon(ii)oxide
(4ci)
-Pb(NO3)2+2NaCl->2NaNO3+PbCl2
(4cii)
-Molar mass of PbCl2=207+(35.5*2)
=207+71=278g/mol
2g will produce 1g of PbCl2
1g will produce 1/2*5.56
278g will produce 1/2*5.56
=0.019C2H3Cl3+HCl
-C2H3Cl3+Cl2-







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