2020 WAEC CHEMISTRY OBJ AND ESSAY VERIFIED ANSWERS / EXPO


(2ai)
The relationship between the compounds A and B is that they have similar chemical properties

(2aii)
– A : Trans-1,2-dichloroethene
– B : Cis-1,2-dichloroethene

(2aiii)
Their chemical properties will be the same

(2aiv)
The reason is because they are geometric isomers. Geometric isomers have the same chemical properties but different physical properties.

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(1ai)
Faraday’s First Law of Electrolysis states that the chemical deposition due to the flow of current through an electrolyte is directly proportional to the quantity of electricity (coulombs) passed through it.

(1aii)
Strong electrolytes ionize completely (100%), while weak electrolytes ionize only partially.

(1b)
CHEMICAL PROPERTY OF EHYNE
– COMBUSTION REACTION: Ethyne burns in air with a luminous smoky flame and hence used for lightening purpose.
2C2H2 + 5O2 —–> 4CO2 + 2H2O + heat

(1c)
Unsaturated hydrocarbons are hydrocarbons that have double or triple covalent bonds between adjacent carbon atoms.

(1cii)
CH3COOH + CH3OH–>CH3COOCH3 + H2O

(1ciii)
methly ethanoate

(1d)
By removing the main product continuously.


(1e)
Mzn = 3.75g
Mzn = 65.0g/mol
n= m/M=3.75/65.0
n=0.0577mole
nH² =0.0577mole because the mole ratio is the same
np =n*L
np=0.0577*6.02*10^23
np=3.47*10^22 moles

(1f)
Flooding

(1gi)
Reaction C

(1gii)
Zinc (from + 2 to + 4)

(1hi)
(i)Each spectral line is caused by one electron
(ii)Electron can exist only in circular orbit of definite quantum energy.

(1hii)
It could not account for the spectrum at note complicated atoms

(1i)
(i)Temperature of the reacting system
(ii)Pressure of the reacting system
(iii)Concentration of the reacting system

(1j)
Both liberate carbon(iv) oxide
One produce a chloride salt , the other produce an ethronate salt

 

 

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