WAEC GCE CHEMISTRY;

Verified CHEMISTRY OBJ:
1-10: DDBCDCBBDC
11-20: CBABCDBCBA
21-30: BCCACABDAB
31-40: AAAACCABBA
41-50: AACBDCDABD 
(1ai) Mass number is the sum of  proton and reaction of an element while Atomic number is the number of protons in an element.
(1aii)
(I) Mass No= proton No + Neutron
34 = proton No + 18
Proton No= 34-18=16
Number of electrons =16
(II)  2,8,6
(1aiii) The relative atomic mass of chloride is not whole number because its exihibit isotopy

(1bi) Transition elements are elements that occupy between period 2 and 3 of the periodic table and have partially filled d-orbitals
(1bii) Copprer , Iron
(1biii)
(I) Because they have partially filled 3d orbitals
(II) Because of the presence of ligands
(1ci) Ionic radius, Electronegativity,electron affinity
(1cii)
(i) Because the distance between the nucleus and neigbouring shell is shorter when compared with Na+
(ii) Because Trioxocarbonate of Na are insoluble in nature.
(1cii)
(i) Because the distance between the nucleus and neigbouring shell is shorter when compared with Na+
(ii) Because Trioxocarbonate of Na are insoluble in nature

(2ai) Graham's law of diffusion states that the rate of diffusion of gas at constant temperature and pressure is inversely proportional to the square root of its vapour density.
(2aii)
(I)  
PB = 1.013*10^5Nm^-3
VB = 5dm^3
Pc= 3.039* 10^5Nm^-2
Vc= 5dm^3
PT= PB+PC
PT = 1.013*10^5+3.03*10^5
PT= 4.052*10^5Nm^-2
(II)
PT=(1.013*10^5*10) + (3.03*10^5*10)
PT= 4.052*10^6Nm^-2

(2bi)
No of mole of methane = 0.50mol,
No of mole of oxygen= 1.5mol,
1mol of methane produces 2 mol of oxygen,
0.50mol of methane produces 2/1 * (0.50) = 1.0 mol of oxygen
Methane is in excess of oxygen
(2bii)
2mol of oxygen produces 2moles of steam,  1.5mol of oxygen produces 2/2*(1.5) = 1.5moles of steam
(2biii)
3.0 = no of molecules/ 6.02*10^23
no of molecules = 3.0*6.02*10^23 = 18.06 * 10^23 particles
=1.806*10^24

(2c) To 1cm^3 of unknown substance, add calcium hydroxide. The presence if milky solution confirms the presence of carbon(iv)oxide
(2di)
(I) By using calcium Chloride
(II) Dry agent
(2dii) Because it is less denser than air
(2diii) Hydrogen perioxide and Cu are formed

(8a)
- Rain
-Spring
-Well
(8b)
i. Alum is added to cause coagulation of particles
ii. To allow for the passage of carbon(iv)oxide
iii. To kill germs
(8c)
i. Sodium hydroxide and hydrogen gas are produced
ii. Water produces colourless solution with copper(II)tetraoxosulphate(iv)

(8di)
(I) paint
(II) Oil
(8dii)  
- Erosion  
- Acid rain
(8diii)
(I) Furing of kettles and boilers stalagmites and stalactites
(II) To remove the hardness in water

(8e)
Al + H2SO4 -> Al2O3 + SO2 + H2  
No of moles of SO2 = 1120/22400 =0.05
0.05 = mass/molar mass
Molar mass of SO2 = 32+(16*2) = 64g/mol
0.05 = mass/64
mass= 0.05 * 64 = 3.2g
3.2g of SO2 produces 2.50g of Al
1g of SO2 produces 2.50g/3.2 of Al
= 2.50/3.2*(27) = 21.09g.
Pure aluminium = 21.09 - 2.50 = 18.59g

(4aii)
- C2H6 contributes to green house effect because it is produced by decomposition of matter.
- C2H4 contributes to green house effect because it is unsaturated and produce smoky flame.
- C2H2 also produce smoky flame
(4aiii) C2H6 is economical because it is saturated

(4b)
(i) Ethanoic acid
(ii) Chloroethane
(iii) Propylhydrogentetra oxosulphate(iv)

WAEC GCE Nigerian Language OBJ & Essay;

Tue. 24th Sept 2013;
Hausa/Igbo/Yoruba (Obj)
= 9am - 10am
Hausa/Igbo/Yoruba
= 2pm - 4pm
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