NABTEB2019 CHEMISTRY QUESTIONS AND ANSWES

 

2019 COMPLETE CHEMISTRY SOLUTION

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NABTEB CHEMISTRY OBJ:


1-10: BCDCDCCDDA
11-20: CDBDBDDCAB
21-30: DBDBACDCBD
31-40: BDCCACABAB
41-50: BBCDCBABBC

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NABTEB CHEMISTRY THEORY

(1ai)
CH3COOH + C2H5OH –> CH3COOC2H4 +H2O
(ethylethanoate)

(1aii) Amino acids

(1aiii) -COOH and -NH

(1bi)
(pick 3)
– They have the same general formula
– They have the same general method of preparation
– They have the same chemical properties
– Successive members are differ by CH2
– The physical property increase steadily with increase in relative molecular mass

(1bii)
(pick 1)
– Methane -CH4
– Ethane – C2H6
– Propane – C3H8
– Butane – C4H10

(1biii)
Carbon. | Hydrogen
Mass – 92.3 | 7.7
Mole – 92.3/12 | 7.7/1
7.69/7.69 | 7.7/7.69
1 | 1

Empirical formula = CH

(1biv)
n(CH)=78
n(12+1)=78
13n=78
n=78/13
n=6
:. The empirical formula =C6H6

(1av)
Benzene C6H6
H
|
C
// \
H-C C-H
| ||
H-C C-H
\\ /
C
|
H

Cyclohexane

H
|
C
/ \
H-C C-H
| |
H-C C-H
\ /
C
|
H

C2H5-C=_(use triple bond)C-C2H5
1,2,- diethylethyne

(1c)
(pick 2)
– It is used for boring holes into rocks
– It is used for cutting glass
– It is used as jewelry

name

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

(2ai)
Le chatelier principle states that if a system is at equilibrium and one part of the system is altered, the equilibrium will shift so as to remove the alterations

(2aii)
N2(g) + 3H2(g) —> 2NH3 ΔH

The conditions that favour a high yield of ammonia are:
– Increasing the concentration of N2 and H2
– Decreasing the temperature of the system
– Increasing the pressure of the system

(2biii)
(i) A thick white smoke of ammonium chloride is formed
(ii) An insoluble pale blue precipitate of copper (II) hydroxide is formed

(2bi)
1s^2

(2bii)
(pick 2)
– It does not support combustions
– It readily liquefies and solidifies on cooling
– It has the ability to sublime at lower temperature ( -780degree)

(2biii)

H
|
C
// \
H-C C-H
| ||
H-C C-H
\\ /
C
|
H

(2ci)
Additional polymerization is the type of polymerization which occur when polymer is formed by the sequential addition of monomer units repeatedly without the co-generation of other product.

(2cii)
Unsaturated Hydrocarbon

(2ciii)
(pick 2)
– Length of the chain of the polymer
– Attractive force between polymer chain
– Branch chain of the polymer
– Cross linking of the polymer

(2d)
DIAGRAM

name
name

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

(3ai)
(pick 2)
– Temperature
– Nature of the substance
– Concentration of the reactant
– Surface area of reactant

(3aiv)
600cm^3

(3av)
18cm^3

(3avi)
50cm^3

(3bi)
TABULATE

– ELECTROVALENT COMPOUND – (pick 3)
– They consist of ions
– They have the ability to conduct electricity
– They have high melting and boiling
– They are soluble in water and insoluble in organic solvent

– COVALENT COMPOUND – (pick 3)
– They consist of molecules
– They do not conduct electricity
– They have low melting and boiling point
– They are insoluble in water and soluble in organic solvent

(3bii)
(pick 2)
– They are good conductors of electricity
– They are lustrous
– They are solid at room temperature except mercury
– They are malleable
– They are ductile
– They have high melting points

(3biii)
Nuclear fission

(3biv)
x is beta particle

(3bv)
(pick 2)
– Scintillation Counter
– Diffusion cloud chamber
– Geiger – Muller counter

(3ci)
Downward delivery

(3cii)
(pick 2)
– Ammonia gas
– Hydrochloride gas
– Sulphur (IV) oxide gas

name
name

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

(4ai)
Allotropy is the existence of a substance in various forms with the same physical state

(4aii)
Rhombic Sulphur

(4aiii)
(pick 1)
– Coal
– Petrol
– Diesel

(4aiv)
It has sharp and suffocating odour

(4bi)
Acid salt are salt that contain a positive metallic or ammonium ion with a negative acid radical ion.
(pick 2)
– NaHSO4
– CaHPO4
– NH4HCO3
– CuHCO3
– MgHSO4

(4bii)
The acid attacks and stains Rutter and cork

(4ci)
CLICK HERE FOR THE IMAGE

(4cii)
At cathode
Calcium ions receive two elections
Ca^2+ + 2e^- —–> Ca(s)

At the anode
The chlorine ions give up an electron each to become atomic chlorine
Cl^- ——> Cl + e^-

(4ciii)
It is used to lower the temperature or melting point from 850degree(c) to 650degree(c)

name

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

(5ai)
Homologous series is a series of compound bond together with a general formula and in which each member differs from the next member by CH2

(5aii)
– Alkanoic acid
– Aminoalkanoic acid

(5aiii)
– Alkanoic acid (pick 1)
* Propanoic acid
* Ethanoic acid
* Butanoic acid

– Aminoalkanoic acid (pick 1)
* Aminoethanoic acid
* Aminoethanoic acid
* Aminobutanoic acid

(5aiv)
(pick 2)
– Natural gas
– Petrol
– Kerosene
– Diesel oil
– Lubricating oil
– Bitumen

(5b)
(i) CaO
(ii) Ca(OH)2
(iii) CaCO3
(iv) CaO
(v) NaOH

(5c)
(i) CuSO2.2H2O = Copper sulphate (vi) dihydrate
(ii) NaHSO4 = Sodium hydrogen sulphate (vi)
(iii) ZnCO3 = Zinc trioxocarbonate (iv)

(5di)
1,2-dichloroethene
Cl Cl
| |
H-C = C-H

(5dii)
Methylethanoate

H O-CH3
| /
H-C-C
| \\
H O

name

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

 

 

 

CHEMISTRY QUESTIONS
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