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Waec 2016/17 Chemistry (Objective & Theory ) Answers Now Available

CHEMISTRY OBJ:
1-10: CAACABCDBC
11-20: BABAADBDCA
21-30: BCCAABCDCB
31-40: ABCBCCCBBC
41-50: ABDBBBAABB



8ai)Each
successive member of a
homologous series differ by
~CH2~group.Members of a
homologous series show
similar chemical
properties. (8biii)C2H5OH
+CH3CH2COOH=CH3CH2COOC2H5
ethylpropanoate (8biii)C2H5OH
+CH3CH2COOH=CH3CH2COOC2H5
ethylpropanoate (8ai)Each
successive member of a
homologous series differ by
~CH2~group.Members of a
homologous series show
similar chemical
properties. (8biii)C2H5OH
+CH3CH2COOH=CH3CH2COOC2H5
ethylpropanoate.

1a )
nucleons is the collective name for two important
sub-atomic particles : neutrons and protons
1b)
Graham 's law of diffusion states that at a
constant temperature and presure , the rate of
diffusion of a gas is inversely proportional to the
square root of it density
1c )
because when aluminum is exposed to moist
air, a thin continuous coating of aluminum oxide
is formed , which prevents futher attack of the
aluminium by atmospheric oxygen and water or
steam under normal conditions
1d)
i ) electron - affinity
ii ) electron - negativity
iii ) ionization - energy
1e )
i ) the molecule of real gases occupies space and
there are forces of the attraction between them
ii ) real gases do liquefy when their temperature
droops .

1f )
i ) used in seperation of different component of
crude oil .
ii )it is used for separating acetonic from water
iii ) it is used for obtaining different gases from air
for industrial use .
1g)
i ) concentration of ions in electrolyte
ii )the nature of the electrode
iii )the position of ions in the electrochemical
series
1h)
i ) substitution reaction
ii )addition reaction
1i )
i ) carbon dioxide
ii )water vapour
iii ) carbon monoxide
1j )
i ) centrifugation
ii )sieving
iii )evaporation to dryness
=====================



3ai) structral isomerism is the existance of two or more compounds ( known as isomers) with the same molecular formula but different molecular structures
3ai) i) tertiary alkanol
ii) secondary alkanol
iii) primary alkanol
3bi) i) 2[CH3 CH2 COOH ] 2K(s)---->
ii) [CH3 CH2 COO ] K + H2
i) 2[CH3 CH2 COOH ] +2 K(s) ------> 2[ CH3 CH2 COO ] K + H2
ii) CH3 CH2 COOH + C4 H9OH HEAT---->CH3 CH2 COO C4 H9 + H20 H2SO4
iii)CH3 CH2 CH2 CH20H + H^+ KMnO4------> CH3 CH2 CH2 CH2 - 0H EXCESS
3bii) i) potassium ethanoate,hydrogen
ii) butyl propanoate and water
iii) enthanal
3c) the percentage composition of the hydrocarbon = 100 H + C = 100 14.3 + C =100 C= 100 - 14.3 C= 85.7% ================ -
4ai) calcium chloride, CaCl2 (4aii) to the unknown ssubstance in a gas jar, add small quantity of lime water. if the gas is carbon(iv)oxide, it turns lime water milky while carbon (ii) oxide has no effect (4bi) oxygen is releasedf abundantly from air and nitrogen is produced by the reaction of potassium trioxonitrate(v) with concentrated hydrochloric acid (4bii) oxygen gas rekindle a lighted splint while nitrogen does not (4ci) Bauxite is preferred because it is readily available in the earth crust (4cii) -trioxosilicate(iii) -carbon(iv)oxide (4ciii) -it helps to purify the bauxite (4civ) it is difficult to extract aluminium by chemical reduction of aluminium oxide in amphoteric (4cv) AL2O3+NaOH=>Na2O + Al+ H20 -
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