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Neco 2016 Chemistry Answers

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Neco 2016 Chemistry Answers
CHEM

CHEMISTRY OBJ: 
1-10: DCBBCBBEDC
11-20: CADECEBBDC
21-30: EEBABDADBE
31-40: AECCACDDDC
41-50: DABABCBBCA
51-60: CBBAABCADE

(5a)
(i) I - Carbon II Oxide and Hydrogen
(ii) II - Carbon II oxide,Nitrogen nd passing air over red hot coke in a furnace

(5aii)
Colloids are mixture in which are substance of micro scopically dispersed insoluble particles is suspended throughout another substances.
Condensation is the change of the physical state of matter from gas phase into liquid phase.

(5bi)
CO2(g) + C(s)------> 2CO(g)

(5bii)
(i) Used as a codant in nuclear reactions.
(ii) Used as a fire extinguisher.
(iii) Green plant use it for photosynthesis.

(5biii)

(I) 
-2=2x+(7x-2)
-2=2x-14 rearrange
2x=-2 + 14
2x = 12
X = +6 oxidation number of chrominum is +6

(II) 
-0 = -2, 5= +6, Cr=x
2x(+6*3+(-2)*4*3)
2x + [+18+(-24) ] = 0
2x+(-6) =0
2x=+6
Therefore x= 16/2 = +3

(5ci)
Vulanization is a chemical process for converting natural rubber or related polymer into more durable materials by adding sulphur or other accelerators.

(5cii) 
Mass*Q
M= IT
t= mass/I =6.35/10.0 = 0.645

(5ciii) 
Latex
===
(4ai)
electrolytic cell is a cell that consist of a container of electrolyte with two electrodes connected to a suitable direct current supply

(4aii)
(i)daniel cell
(ii)Leclanché cell

(4aiii)
(i)copper
(ii)tin

(4aiv)
action of dilute acide on zinc

(4av)
Zn+2HCl------>ZnCl+H2

(4bi)
(i)dinitrogen(i)oxide(N2O)
(ii)nitrogen(v)oxide(N2O5)
(iii)nitrogen(iv)oxide(NO2)

(4bii)
charle's law states that the volume of a fixed mass of gas varies directly with the absolute(kelvin)temperature provided the pressure remains constant.

(4biii)
P1 V1 = P2 V2
given that
P1 = 900mmHg
P2 = 750mmHg
V1 = 300cm^3
V2 = ?
V2 = P1V1/P2
V2 = 900*300/750
V2 = 270000/750
V2 = 360cm^3

(4biv)
% composition carbon
= 12/(12*6) + (1*6) *100%
= 12/72+6 *100
= 12/78 * 100% = 1200/78%
%composition of carbon = 15.38%

(4c)
Tabulate:
-Thermoplasts:
(i)it melts when heat is applied to it
(ii)highly recycled

-Thermosets:
(i)does not melt when heat is applied
(ii)cannot be recycled

================================

(1ai)
A mixture contains two or more constituents which can easily be seperated by physical methods

(1aii)
magnesium trioxonitrate(v) = Mg(NO3)2
molar mass of Mg(NO3)2
=(1*24) + 2 (14*1 + 16*3)
=24 + 2 (14 + 48)
=24 + 28 + 96 = 148g/mol
% of nitrogen = 2*24*100/148
% of nitrogen = 48*100/148
% of nitrogen = 4800/148
% of nitrogen = 32.43%

(1aiii)
(i)calcium oxide (CaO)
(ii)calcium choride (CaCl2)

(1bi)
CnH2n+1OH

(1bii)
hydrolysis

(1biii)
(i)displacement reaction
(ii)double decomposition reaction
(iii)decomposition reaction
(iv)catalytic reaction
(v)reversible reaction

(1biv)
(i)endothermic heat change
(ii)exothermic heat change

(1ci)
(i)methyl orange
(ii)phenolphthalein
(iii)litmus

(1cii)
NH4Cl+Ca(OH)2----->CaCl2+2NH3+2H2O

(1ciii)
it is collected by upward delivery

(1civ)
mass of gas = 1.58*22.4 = 35.392
vapour density = 35.392/1
relative molecular mass= V . D * 2
=35.392*2
relative molecular mass= 70.784

====================================

(6ai)
-addition of water to calcium oxide
-rusting of iron in moist air

(6aii)
-Enhanced weathering
-Direct air capture
-Bio-energy with carbon capture & storage

(6aiii) 
Enhanced weathering equation
CaCO3 + CO2 + H2O → Ca2+ + 2HCO3−

(6aiv)
Because it is an oxidizing agent

(6bi)
Physical properties of Ethene:
-It is neutral to litmus paper
-It is slightly less dense than air

Physical properties of Ethanol:
-It is readily soluble in water in all proportions
-Ethanol is a colourless, volatile liquid with a characteristic taste and smell

(6bii)
CH3CH2OH-------->CH3COOH

(6biii) 
sp3-hybridized molecule.


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