28/07/2021
CHEMISTRY-OBJ
01-10: EECBBAEBBB
11-20: DDDBEAEABB
21-30: DBECCDAAAB
31-40: BADCBACDAC
41-50: CECCEADBDC
51-60: CEBEEDDBAE
Completed.
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CHEMISTRY-THEORY
(1ai)
(i) Base has bitter taste
(ii) Base is soapy to touch
(iii) Base turns litmus paper blue
(1aii)
The steps involved are:
(i)Shift conversion
(ii)Removal of carbon (iv) oxide
(iii)Steam reforming
(1aiii)
Cracking is the process by which heavier hydrocarbon molecule is splitted into two or more lighter molecules
(1aiv)
Thermal cracking
(1bi)
P ion = 1s²2s²2p⁶
(1bii)
Formula of chloride is Pcl2
(1biii)
Reducing agent
This is because it undergoes oxidation by losing electrons
(1ci)
Electron affinity is the energy released when a gaseous atom gains an electron to form a gaseous negative ion.
(1cii)
This is because it has lone pairs of electrons
(1di)
(i) By adding a catalyst
(ii) FeS(s) + 2HCl(g) -----> FeCl(g) + H2S(s)
Xg = ?
No. of FeCl2 = 127g/mole
No. of FeS= 88g/mole
Mole = Mass/ No. of Mass = 3.2/127 = 0.025mole of FeCl2
By comparison,
1 mole of FeS = 1 mole of FeCl2
X moles of FeS = 0.025 of FeCl2
X = 0.025mole of FeS
Recall,
Mass = Mole * molar mass
Mass = 0.025*88
Mass = 2.2g of FeS
X = 2.2g
(1dii)
(i)Chlorofluorocarbons
(ii)Ammonia
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(2ai)
(i)Molecules of gases are in constant random motion
(ii)The collision of gases is perfectly elastic
(iii)An increase in temperature leads to an increase in the average kinetic energy of the molecules of gases
(2aii)
(i)They both turn blue litmus paper red
(ii)They both dissolve in water to produce an acid
(2aiii)
Copper 2KNO2(s) + O2(g)
(NH)CO3(s) ------>2NH3(g) + CO2(g) + H2O(g)
(iii) No. of molecules = 4/16 × 6.02 × 10²³
= 1.5 × 10²³
(4di)
(i)Sodium
(ii)Potassium
(4dii)
(i)Carbon (iv) oxide
(ii)Carbon
(4diii)
(i)Hydration
(ii)Oxidation
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(5ai)
Gay Lussac states that when gases react, they do so in volume which bears a simple whole-number ratio to one another and the volume of their products.
(5aii)
2CO + O2 ----> 2CO2
2 1 2
100cm³ 70cm³ 100cm³
Total volume = 100+70+100 = 270cm³
(5bi)
(i)It is used in the production of other chemical substances
(ii)It is used as a drying or dehydrating agent
(5bii)
(i) ZnCO3 -----> ZnO + CO2
->Conditions ZnSO4 + H2
->Conditions
