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👑 2018 NECO GCE CHEMISTRY ANSWERS👑
100% VERIFIED CHEMISTRY OBJ ANSWERS
100% VERIFIED CHEMISTRY THEORY ANSWERS
(I) Electrolytes are the components that conducts electricity in molten form or in solution
(II) Electrolysis is the chemical decomposition of a substance brought about by a direct current passing through either a solutions of or a Molten form.
11R => Na – Sodium
17S => Cl – Chloride
(2bii) Electrovalent bond
(i) It is used as bleaching Agents
(ii) For making important chemicals such as Hcl
8Q has the lowest ionization energy
(i) 11R ==> Sodium has low I.E
(ii) Fe (iron) react with cold water to form Iron (iii) tetroxide with the release of hydrogen but slow of the iron not hot
(I) Sodium: Sodium (Na) is a highly unstable alkali metal. It needs to give up one electron to become stable. When a cubic centimeter sized piece of sodium is placed into cold water, a vigorous chemical reaction occurs in which sodium hydroxide (NaOH) and hydrogen gas is produced
Iron: They react with water to form the metal oxide and hydrogen.
When water is added to blue anhydrous copper (ii) chloride the colour changes from blue to pink
Gay lussac’s law of combining volumes states that if gases react they do so in volume which bears a simple ratios and to the volume of the product. If gaseous provided that the temperature and pressure remains constant.
V1/T1 = V2/T2
250/298 = 500/T2
280 T2 = 500 x 298
T2 = 500 x 298/250 = 596K
A atomicity of an element is the total number of an atoms present in one molecule of an element or a compound.
(I) Mono atomic – Helium ,Neon
(II) Triatomic – Ozone (03)
(i) it is used as antiseptic
(ii) it is used in bleaching delicate material last such as silk, wool, wood pulp etc
(i)it is a colourless, odourless gas
(ii)it is neutral to moist litmus paper
(i) To help reduction of impurities
(ii) To avoid other constituents from sticking to them
(iii) It is cheaper to use
CuCO(s) —> CuO + CO2
1 mole of CuCO3 produces 1 mole of CO2
0.081moles would give 0.081moles of CO2.
No of mole = mass/Molar mass
CuCO(s) = 123.5 = 10/123.5
No of mole of CO2 = Volume given/22.4
0.081 = volume/22.4
V = 22.4*0.081
Endothermic | Exothermic
(i) heat is absorbed to the surroundings
(ii) The Enthalpy change is posture (+ve)
(i) Heat is evolved to the surroundings
(ii) The enthalpy changes here is negative
(i) Sodium hydroxide pellets in water is Exothermic
(ii) Ammonium Chloride in water is Endothermic
(iii) Con H2SO4 acid is Exothermic
Saturated Fatty Acids | Unsaturated Fatty Acids
UNDER SATURATED FATTY ACIDS:
-Their bonds to accepts any form of constituents are full
UNSATURATED FATTY ACIDS:
-They still have more bond space so they are Unsaturated
Fatty acid are work acids because they dissociate partially in water and the Hydrogen or Hydroxonium ions are not concentrated
DRAW THE STRUCTURE
(i) They are used as fragrance
(ii) They are used as plasticizers.
Platinum electrode: Copper ion will move to the anode
Copper electrode: Hydrogen ion will migrate to the cathode
Oxides A B
Mass of Sulphur 7.00g 5.60g
Mass of Oxygen 12.0g 19.1g
20/7* 12 20/5.6*19.1
Allotropy is a phenomenon in which elements exist in various forms having different physical properties but the same chemical properties.
(I) Coal tar and coke
(II) carbon dioxide and water
(i) It is heavier than air
(ii) It does not support combustion
(i) It produces branched chained alkanes which improves octane rating of petrol.
(ii) It requires less amount of energy.
In a tabular form
(i) It is easily reversible.
(ii) No new substance is formed.
(i) It is not easily reversible.
(ii) New substances are usually formed.
(i) It can be separated by physical method.
(ii) Air varies in composition as a result of pollution.
(iii) Air shows the properties of all the gases present in it.
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