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SOLUTIONS
WAEC GCE CHEMISTRY
(1ai)
Mole is the amount of substance of a system which contains as many elementary entities as there are atoms in 0.012 kilogram of carbon 12. its symbol is MOL
(1b)
(CHOOSE ONLY ONE)
(i) Incomplete combustion i.e less oxygen for combustion produces a mix of carbon, carbon dioxide, carbon monoxide and water.
(ii) Carbon monoxide (CO) & Carbon particles (soot)
(1c)
(i) Dispersion (weak).
(ii) dipole-dipole (medium).
(iii) hydrogen (strong).
(1d)
Brownian motion refers to the random movement displayed by small particles that are suspended in fluids. It is commonly referred to as Brownian movement”. This motion is a result of the collisions of the particles with other fast-moving particles in the fluid.
(1e)
Condensation Polymerization: It is form of a step-growth polymerization where smaller molecules or monomers react with each other to form larger structural units (usually polymers) while releasing by-products such as water or methanol molecule. The by-products are normally referred to as condensate.
(1f)
(i) 2-methyl propane.
(ii) 3-Chlorobutanoic acid.
(1g)
(i) The oxidation number of iodine in the potassium periodate molecule is 7.
This molecule is ionic which means that the periodate ion has a charge of 1- in order to balance the 1+ charge on the potassium ion.
Since the oxygen molecules combine for an oxidation number of 8 (4×2=8) this gives us a total oxidation number of 8−1=7
(ii) Let, X be the oxidation state of bromine in HBrO
+1 + X + (-2) = 0
1 + X − 2 = 0
X − 1 = 0
X = + 1
Hence, the oxidation state of Br in HBr03 is +1
(1h)
(i) Cathode rays consist of negatively charged particles. When cathode rays are subjected to an electrical field, these get deflected towards the positively charge plate i.e. Anode. We know that a positively charged body would attract only a negatively charged body, therefore the particles of cathode rays carry negative charge. Cathode rays also get deflected when these are subjected to a strong magnetic field. The electrons in the cathode rays would deflect toward the positively charged plates, and away from the negatively charged plates.
(ii) It shows that cathode rays consist of material particles having mass and velocity.
3ai] Electrode potential is defined as the potential of a cell consisting of the electrode acting as a cathode and the standard hydrogen electrode acting as an anode. Reduction always takes place at the cathode, and oxidation at the anode.
3aii] * It is used to measure the relative strength of different oxidants and reactants.
* Standard Cell Potential Value is calculated for various chemical species.
* Used to predict if certain chemical species will react with each other and to what extent that reaction will be.
* It is used to predict the point of equilibrium in a chemical reaction.
3bi] Law of Compound Composition states that in any particular chemical compound, all samples of that compound will be made up of the same elements in the same proportion or ratio.
(3ci) Na>Mg>Al
(3cii).
I) Na
II) Al
(3ei). One of the main reasons for classifying organic compounds by their functional groups is that it also classifies their chemical behavior.
(3eii). Ethene gas, C2H4, reacts with water at high temperature to yield ethyl alcohol, C2H6O.
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