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100% NECO 2014 Chemistry Answers Available Here


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ANSWERS

1a)
Atomicity is the number of atoms in a
molecule of an element

1aii)
Mass number of an element is the sum of the
proton number and
the neutron number

1aiii)
Isotopy is the existence of atom of the same
element that have
the same atomic number but different mass
number

1bi)
The reaction is a displacement reaction because
Zinc will
displaced hydrogen from hydrochloric acid
because it is above hydrogen
in the activity series.
There is an effervescence & hydrogen gas is
given off the gas is
collected over water because it is insoluble in
water
Zn Hcl ----------- Zncl2 H20

1bii)
It is used in filling ballons because it has a low
density
* it is used in hardening Fat and oils in the
manufacture of margine
and other solid fats
* it is used in the manufacture of ammonia in
the harber process

1c)
Molar mass of HNO3 = 1 14 (16)3 = 63g/mol
% of oxygen = (16)3/63 x 100% = 76.19%

1d)
* copper
* iron
* Tin
* Aluminium

1e)
* Sodiumtetrahy-droxozinate(ii) --------- Na2Zn
(OH)4
* sodiumoxonitrate(iii) --------- NaNo2

1eii)
Used in soap making
* used to soften hard water
* used as fertilizer
* sodium chloride is used as preservative for
meat and fish


2a)
cassiterite

2aii)
Sn02 2c(s) -------------> Sn(s) 2CO(g)

2aiii)
* Ethanoic acid from vinegars
* Tartaric acid from grapes
* Lactic acid from milk
* Amino acid from protein

2bi)
* used in making cooking utensils
* used in making alloy
* used in making overhead electric cable

2bii)
* Increasing the concentration
* Increasing the temperature of a system
* Increasing the surface area of magnesium

2biii)
Mg 2HCL -------------> Mgcl H2

2c)
* Downward delivery or upward displacement
of air
* hydrogen chloride gas
* ammonia gas
* solubility

2di)
The heat involved when one mole of
substance is burned completely in
oxygen under standard condition

(2dii)
DG = DH - TDS
= -710 - (300 x 0.15) = -755kg/mol

(2diii)
* It alters the rate of chemical reactions
* it is specific in action
* it cannot start a reactions
* it has no effect on the equilibrium position of
a reversible reaction



3a)
* Double decomposition reaction
* Redox reaction
* Displacement reaction

3bi).
(I) R - OH (ii) R - COOH (iii) R - C=O-R
Where R= alkyl group = CnH2n 1

3bii)
CnH2n-2
3biii)
* All members can be prepared by the same
general method
* They have similar chemical properties
* They share same general molecular formula
* Each successive member differ by -CH2

3ci)
* Hydrogentetraoxosulphate(vi)acid [ H2So4 ]
* Hydrogentrioxonitrate(v)acid [ HNO3 ]
* Hydrochloric acid [ HCL ]

3cii)
Ethanol ,
* propan-2-ol

3d)
19A »»» 1s2, 2s2, 2p6, 3s2, 3p6, 4s1
9B »»» 1s2, 2s2, 2p5

3dii)
ElectRovalent bond

3diii)
Soluble in water
* Insolube in organic solvent
* Conduct electricity in aqueous

3e)
diff in solubility from 100oc to 15oc = 39.8 -
35.9= 3.9g
I.E solute deposited on cooling, on cooling
from 100oc to 15oc,
Mass involved at 100oc= 39.8g 1000g of water
= 1039.8g
Mass involved at 15oc= 35.9g 1000g of water =
1035.9g
Ie 1039.8g of saturated solution deposited 3.9g
of solute.
Ie 80g of saturated solution deposite --------
3.9 x 80/1039.8= 0.30g of water



4a)
Allotropy is the existence in the same physical
state of two or
more structural forms of the same element

4aii)
Rhombic sulphur
* Monoclinic sulphur
* Amorphous sulphur
* Plastic sulphur

4b)
cracking process
* C8H18 - octane
* It reduce knocking

4c)
Addition polymerization
* Condensation polymerization

4cii)
hardness of water ia a suitation whereby water
does not lather
easily with soap

4d)
octane salting is a figure indicating the
antiknock properties of
a fuel based on a comparison with a mixture of
isoctane & heptane

4dii)
Cracking: this is whereby complex molecule
are broken down into
simpler molecule. While,
Reforming: is the process used to convest
molecule having low octane
rating into high octane liquid product

4diii) Cu2 2e- ----------> Cu
2F ------------> 1 mole
2 x 96500c ----------> 1 mole
482.5c -------------> M/64
2 x 96500 x M/64=482.5
M= 0.16g

4e) chlorofluoro carbon
* Carbon(ii)oxide
* Sulphur(iv)oxide



5a) An aerosol is a colloid of fine solid particles
or liquid droplets in air or another gas
* An emulsion is a collided solution of liquid in
liquid

5aii) Haze. (ii) Milk

5aiii) Harber process
* Hydrogenation process

5b) Fractional distillation

5bii) High inflammable
* insoluble in water
* Good organic solvent

5c) used in manufacture of HCL
* for water purification
* dyeing industry
* manufacture of organic substance

5cii) SOLID: molecule are fixed and tightly
packed
* It has a definite shape
* they are compacted together
LIQUID: molecule are loose
* it takes shape of the container
* it moves freely

5d) HCL NAOH --------> NACL H20
Ca=? , Va=20.30cm ie 20.30 x 10^-3dm3,
Vb= 25 x 10^-3 , Cb=0.1
Ca = 0.1 x 25x10^-3/20.30 x 10^-3
Ca = 0.123mol/dm3



6a) standard heat of naturalization is the heat
change when one mole of hydrogen ion from
acid react with one mole of hydroxide ion from
an alkaline to form one mole of water under
standard conditions

6aii) Conc H2S04 , conc HCL ,
Aluminiumtetraoxosulphate(vi)

6aiii) Temperature , Amount of solute in
solvent

6b) As fire extinguisher
* in photosynthesis process
* in the solvay process
* As coolant in nuclear reactions -


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1 . DABDADABDA
11 . EEDAEADDBB
21 . AABDEABDDD
31 . DBCCAAAACA
41 . EACEEEEAAA
51 . EEBCABBACA







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