100% Verified NABTEB GCE Chemistry Questions and Expo Answer – Nov/Dec 2017
NABTEB GCE 2017 Nov/Dec Chemistry OBJ and Essay Answer and Solution to the questions.
In a degenerated orbital there are no two electrons that can have the same four Quantum numbers.
i)An ionic bond involves the loose and gain of electrons.
ii)A covalent bond involves the sharing of electrons by two atoms where both atoms contribute.
iii)A dative bond involves sharing of electrons but only one atom contribute the electrons to be shared
Periodic law states that atoms are arranged in order Of increase in their atomic number
i)Does not form common compounds – k10
ii)liberates hydrogen from cold water – J3
iii)Are halogens – N17
iv)Are in the same group – J31L13
v)Forms ions by loss of three electrons – L13
– Ammonia – Triangular pyramid
– Methane – Tetrahedral
– sulphur (iv) oxide – linear
LAW OF CONSTANT COMPOSITION: states that all pure sample of a particular chemical compound contain the same elements combined in the same proportion by mass.
-sample C: 5.00/4.06×100/1
-sample D: 6.60/5.35×100/1
sample c: 123g
sample d: 123g
hence, the percentatge by mass is the same, this proved the law of definite(constant) proportion.
AMPHOTERIC OXIDE: are oxides of metals which can behave both as basic oxides and as acidic oxides i.e they can react with both acids and alkalics to form salts and water only.
i)ZNo: formed from 2ZN(s)+O2 –> 2Zno
hence; Zno(s)+H2So4(aq) –> ZnSO4(aq)+H2O(i)
ii)Al2O3: formed from 4Al(s)+3O2(g) –> 2Al2O3(s)
iii)Pbo: formed from 2pb(s)+O2(g) –> Pbo(s)
Therefore: amphoteric acide from Zno above shows that, amphoteric oxides behave as basis forming a salt and water only.
i)Acidic oxides e.g CO2, SO4, NO2, e.t.c
ii)basic oxides e.g Na2O, CaO
A hypothetical gas that obeys exactly all postulates of the kinetic-molecular theory.
i)change in temperature
ii)variation in earth gravitation
iii)gas forms a liquid – condensation
iv)liquid forms a gas – evaporation
v)gas forms a solid – sublimation
Allotropes are atoms of the same element in the same physical state but in different forms.
*Very strong solid
Diamond -> For cutting glass
For drilling limestones
Graphite -> For making pencils
For lubricating metals
An electrolytic cell is made up of an electrolyte, electrodes and sources of electricity where the electrolyte decomposes.
2 Faraday deposits 63.5g of copper
i.e 2x96500c deposits 63.5g of copper
298,500c deposits Xg of copper
X = 298,500×63.5 / 2×96500
A reducing agent is the substance that is oxides in a redox reaction
They will turn purple permanent to pink.
i)Pipeline product manufacturing company in portharcourt
ii)Dangote cement in lokoja
A saturated solution contains the maximum amount of solute that the solvent can take at a particular temperature.
A dilute solution contains more solution that solute contain at a temperature.
A super saturated solution contains more than enough solute than the solvent can contain at the temperature.
Chlorine – For killing micro organisms
Alum – For coagulation
i)It reacts with water to form acid
ii)It changes blue litmus paper to red
iii)It reacts with ammonia gas to form salt.
i)As an oxidising agent because it reduced to nitrogen gas.
ii)As an acidic oxide because the product formed are salt and water only.
Disco sulphate(iii) acid – Hso2
C2HSOH ——-> C2H4+H20
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