NABTEB 2016 Chemistry (Obj and Essay)  Essay and Obj & Theory Answer Now Available -MAY/JUNE

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Chem-obj

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1a)
i)the gas molecules moves in straight lines colliding with one another
ii)the collisions of the gas molecules are perfectly elastic
iii)the cohesive forces between the gas molecules is perfectly elastic
1aii)
V1/T1=V2/T2
where V1=125cm^3
V2=? T1=17dgree census, T2=100dgree census
125/17=V2/100
12500/17=V2
V2=735.29cm^3
1bi)
tabulate
i)Acidic- NO2,P4O10
ii)Basic-Na2O,C4O
iii)neutral-CO,N2O
iv)Amphoteric-AL2O3,ZnO
1bii)
acid is any substance which produces hydrogen ion H^+ or hydrozonium as the only positive ion when reacted with water
1ci)
the raw materials are sulplur,oxygen,tetraoxo-sulphate(vi)acid,vanadium(v)oxide and air
1cii)2So2+O2<—– —–> 2SO3+Heat
1ciii)vanadium(V)oxide
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2ai)
(39)(19)K
Period 4 , Group 1
19 = 1 S ^ 22 S ^ 22 P ^ 2 x2 P ^ 2 P ^ 2 Z3 S ^ 23 P ^ 2 X 3 p ^ 2 y 3 P ^ 2 Z4 S ^ 1
2aii)
(24 )(12 )Mg
Period 3 , Group 2
12 = 1 S ^ 22 S ^ 22 p^ 2 x 2 P ^ 2 y 2 p^ 2 Z3 S ^ 2
2aiii)
(32)(16)S
Period 3 , Group 6
1 S ^ 22 S ^ 22 P ^ 2 x 2 P ^ 2 y 2 P ^ 2 Z3 S ^ 23 P ^ 2 x 3 P ^ 2 y 3 P ^ 2 Z
2bi)
They have their spin numbers parallel to each other
2bii)
They are used as catalyst because they retain their chemical properties when subjected to change in physical nature
2biii)
They form coloured ions because gthey have different sub- orbitals of d whose wavelength is the same with that of electronic radiations
2ci)
Acid anhydride are chemical substance which dissolves in wateer to give hydrogen ions eg H 2 SO3 , HNO2
2cii)
HNO2 , H 2 SO3
2ciii)
They contain ioons which are mobile in water
-They are usually solids and liquids
-They conduct electricity in molten form
-They dissolve in polar solvent eg water
-They are insoluble in non polar solvent eg ethanol
2di)
-They have high boiling point
-They have high melting point
-They are ductile ie they can be drawn into shapes
-They are malleable
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3ai)
It states that all pure samples of the same compound contain the same elements combine in the same proportion by mass
3aii)
-They have the s sub orbital
-They are soft metals
-They occupy group1 of the periodic table
-Their carbonates are soluble in water
-They are the most electropositive metals
-Their nitrates decompose to give nitrites and oxygen
2 NaNO3 – > 2 NaNO2 (s ) O 2 (g)
3b)
Using dilution formular
C 1 V 1 =C 2 V 2
25 * 1 =0 .2 * V 2
V 2 =25 * 1 / 0 . 2
V 2 =125 cm ^ 3
3ci)
-Fat are solids , oils are liquids
-Fats have high boiling point oil have low boiling point
3cii)
Vegetable oil can be converted to margarine by the process called Hydrogenation. By passing the hydrogen into oil at a temperature of 200 degrees C using Nickel or platinum catalyst , The liquid oil is converted into solid fat
3ciii)
Potasium heptadicromate VI .Na2 Cr 2 O 7
3d)
2 Zn(NO 3 )2 (s )- > 2 ZnO (s ) 2 NO 2 (g) 3 O 2 (g)
3dii)
Nitroen IV oxide and oxygen
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5ai)
(C 6 H10 O 5 )n – > C 12 H 22 O 11
C 12 H 22 O 11 – > (H 2 O )C 6 H 12 O 6 C 6 H 12 O6
C 6 H12 O 6 – > 2 C 2 H5 OH (l) 2 CO2 (g )
5aii)
-It is miscible with water in al proportions
-Igt is neutral to litmus paper
-The boiling point is 78 degrees C
5bi)
HCOOH- Methanoic acid
CH3 COOH – Ethanoic acid
C 2 H5 COOH – Propanoic acid
5bii)
Esterification
5c)
C H O
(54 . 5 / 12 ) (9 . 10 / 1 ) (36 . 4 / 16 )
4 .54 9 .10 2 . 275
Divide by the smallest value
(4 .54 / 2 .275 ) (9 .10 / 2 . 275 ) (2 . 275 / 2 . 275 )
1 .99 4 1
2 4 1
C 2 H4 O ethanol

 

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