100% NECO 2014 Chemistry Answers Available Here

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)
Electovalent 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