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Chemistry Password

(CHEMISTRY OBJ
1-10: CACDBDADAD
11-20: AADCDABBCD
21-30: BACBCCBCAC
31-40: CBACBCDBAD
41-50: DBBDCBCCCB

1ai)
Faraday’s first law of electrolysis states that the mass(m) of an element discharged during electrolysis is directly proportional to the quantity of electricity(Q) passing through it.

(1aii)
(i) Strong electrolytes conduct large currents while Weak electrolytes do not conduct current readily.
(ii) Strong electrolytes ionize completely while weak electrolytes ionize only slightly.

(1b)
Ethyne burns in air to give a smoky and luminous flame (complete combustion)

(1ci)
If an organic compound contains carbon atoms joined by double or triple covalent bonds. The compound is said to be an unsaturated hydrocarbon.

1cii)
CH3COOH(aq) + CH3OH(aq) <–> CH3COOCH3(l) + H2O(l)

(1ciii)
Methyl ethanoate

(1d)
By removing the main product continuously

(1e)
Number of moles of Zn dust = Mass/molars mass = 3.75/65 =0.0077
Reacting mole ratio of Zn to H2 is 1:1
:’ No of moles of H2 produced =0.0677 moles
1 mole = 6.02×10²³ molecules
0.0577moles of hydrogen produces
=6.02×10²³ x0.0577
=0.347×10²³ molecules
Or 3.47×10²² molecules

(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)
(i) Both liberate carbon(iv) oxide
(ii) One produce a chloride salt , the other produce an ethanoate salt

SECTION B..

2ai) isomers

2aii) A = trans 1,2 dichloroethane

B=Cis 1,2 dichloroethane 2aiii) Yes.

2aiv)Because they are isomers. Isomers have same chemical properties but different physical properties.

2b) Destroying gaseous emissions

– Boiling is the rapid vaporization of a liquid 2bii) – WHEN NACL IS ADDED =>The more salt (or any

solute) added to water, the more you raise the boiling point. Reduction of atmospheric pressure => lowering the atmospheric pressure will lower the boiling point of the liquid.

2c) A saturated solution contains the maximum amount of solute that will dissolve at that temperature. Any further addition of solute will result in undissolved solid on the bottom of the container. An unsaturated solution contains less than the maximum amount of solute that can be dissolved at that temperature.

2cii) -Add solute to a liquid until no more will dissolve. -Solubility often increases with temperature, so you may be able to get more solute into a hot solvent than you would if – Increase in pressure

the solvent was cool

2cii)Temperature and Pressure.

Temperature affects the solubility of both solids and gases,

-Pressure only affects the solubility of gases

2ciii)
Temperature.

(2di)
Mole is a standard scientific unit for measuring large quantities of very small entities such as atoms, molecules, or other specified particles

(2dii)
MgO(s)+2HCl(aq) —> MgCl(aq)+H2O(l)
From the equation of reaction; 1 mole of MgO = 2 moles of HCl
Hence n = cv/100
where c = 0.1moldm-³; v = 25.0cm³
No of mole of HCl = n = 0.1×25/1000
= 2.5 x 10-³ moles
Hence the no of moles ofMgO required = 2.5/2 x10-³
But n = m/M = reacting mass/ Molar mass —> m = nM = 1.25×10-³ x 40
= 50 x 10-³ = 0.05g of MgO.

(2e)
(i) They are malleable
(ii) They are ductile
(iii) They are good conductors of heat and electricity

(3ai)
Draw the diagram

(3aii)
I. Activation Energy = (210 – 100)KJ = 110K
II. Hp – HR = ΔH
54 – 100 = -46KJ

(3aiii)
Q2(g) + R2(g) –> 2QR(g)

(3aiv)
Exothermic reaction.

(3av)
The heat content of the reactant is higher than that of the product.

(3bi)
E7 – 1s² 2S² 2P³
F9 – 1s² 2S² 2P⁵
G12 – 1S² 2S² 2P⁶ 3S²
H13 – 1S² 2s² 2P⁶ 3S² 3P¹

(3bii)
I. G and H
II. H
III. F
IV. GF2

(3ci)
Isotopy is the existence of an element in more than one physical form with the same atomic number but different atomic masses.

(3d)
(i) Atoms
(ii) Molecules
(iii) ions

(5ai)
(i) Ammonia (NH3)
(ii) Hydrogen chloride gas(HCl)

(5aii)
To show that hydrogen chloride is extremely soluble in water.

(5aiii)
Fill a round-bottomed flask with dry hydrogen chloride through a tube A and air through another tube B. Add a few drops of water through B and close the tubes. Invert the flask into a trough of water containing blue litmus solution. The water turns red.

(5bi)
Petrochemical industries.
Pharmaceutical industries.

(5bii)
(i) Pollution of water bodies by chemical waste.
(ii) Pollution of air.
(iii) Radioactive particles are released.

(5ci)
(i) Coke.
(ii) Coal tar.
(iii) Coal gas.

(5cii)
(i) Coal gas –> Importsmt gaseous fuel.
(ii) Coke –> Used as a reducing agent.

(5di)
(i) Calcium tetraoxosulphate(vi)
(ii) Calcium hydrogentrioxocarbonate(iv)

(5dii)
(i) By boiling.
(ii) Addition of caustic Soda.

(5diii)
(i) Hard water contains dissolved minerals and therefore tastes better.
(ii) The calcium salts on hard water help animals to build strong teeth and bones.

Posted by on September 2, 2020.

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