(Posted) 2015 WAEC GCE CHEMISTRY OBJ AND THEORY FOR FREE

CHEMISTRY OBJ:
1-10: AABABACACA
11-20: DABAAACDDB
21-30: ADDCCDCDCC
31-40: AACCADCDAB
41-50: ADDCCBAACD
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(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
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
3 ai )
CH 3 CH = CHCH# is alkene
CH 3 COOCH3 is alkanoate
CH 3 CH ( OH ) CH 2 CH 3 is alkanol
CH 3 ( CH 2 ) 2 CH 3 is alkane
ii ) - But - 2 - ene
- ethyl ethanoate
- Butane
- But - 2 - ol
iii) CH 3 ( CH 2 ) 2 2 bi )
- Ultraviolet light ii )
C2 H6 Cl 2 - > C2 H5 Cl HCl
iii)
- C 2 H 5 Cl Cl 2 - > C2 H4 Cl 2 HCl
- C 2 H 4 Cl 2 Cl 2 - > C 2 H 3 Cl 3 HCl
- C 2 H 3 Cl 3 Cl 2 - > C 2 H 2 Cl 4 HCl
- C 2 H 2 Cl 4 Cl 4 Cl 2 - > C 2 HCl5 HCl
- C 2 HCl5 Cl 2 - > C2 Cl 6 HCl
iv)
Hexachloroethane
° ° ° ° ° ° ° ° ° ° ° ° ° ° ° ° ° ° ° ° ° ° ° ° ° ° ° ° ° ° ° ° ° ° ° ° ° ° ° ° °
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)->CO2(g)
2C(s)+O2(g)->2CO(g) iii)
-Carbon(iv)Oxide
-Carbon(ii)oxide
4ci)
-Pb(NO3)2+2NaCl->2NaNO3+PbCl2
ii) -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
=0.019

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