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Chemistry
UTME / JAMB 2008
Stoichiometry, Mole Concept & Volumetric Analysis
Solution
0.05 mol dm-3 HCl is neutralized by 25 cm3 NaOH. If the volume of acid used is 32.00cm3, what is the concentration of the base
A
0.016 mol dm-3
B
0.032 mol dm-3
C
0.039 mol dm-3
D
0.064 mol dm-3
medium Difficulty
Verified Correct Answer: Option D
Chemical Principles & Mechanism
HCl + NaOH → NaCl + H2O
CAVA = NA/NB = (0.05 * 32)/(CB * 25)
∴ CB = (0.05 * 32)/25 = 0.064 mol dm-3
Source: Myschool Past Questions Archive (Record #4045)
Chemistry
UTME / JAMB 2008
Oxidation, Reduction & Redox Reactions
Solution
The oxidation state of carbon in HCOOH is
A
-1
B
+2
C
+3
D
zero
medium Difficulty
Verified Correct Answer: Option B
Chemical Principles & Mechanism
HCOOH
O.N of H + O.N of C + 2* O.N of oxygen of
H = 0
1 + X + 2X - 2 + 1 = 0
2 + X -4 = 0
X = 4 - 2 = +2
Source: Myschool Past Questions Archive (Record #4048)
Chemistry
UTME / JAMB 2008
Stoichiometry, Mole Concept & Volumetric Analysis
Solution
What is the IUPAC nomenclature of the compound NaCIO?
A
sodium oxochlorate (I)
B
sodium chloro (I) oxide
C
sodium monooxochlorate (II)
D
sodium chloro (I) monoxide
medium Difficulty
Verified Correct Answer: Option A
Chemical Principles & Mechanism
NaClO is sodium oxochlorate(I) in IUPAC nomenclature
Source: Myschool Past Questions Archive (Record #4050)
Chemistry
UTME / JAMB 2008
Electrolysis & Electrochemical Cells
Solution
In recharging a lead-acid accumulator, the reaction at the cathode can be represented as
A
Pb2+(aq) + SO2-4(aq) →PbSO4(s)
B
Pb2+(aq) + 2e- →Pb(s)
C
Pb2+(aq) + 2H2O(l) → PbO2(s) + 4H+(aq) + 4e-
D
Pb(s) → Pb2+(aq) + 2e-
medium Difficulty
Verified Correct Answer: Option B
Chemical Principles & Mechanism
In lead acid ,lead dissociates at the cathode Pb2+(aq) + 2e- →Pb(s)
Source: Myschool Past Questions Archive (Record #4055)
Chemistry
UTME / JAMB 2008
Electrolysis & Electrochemical Cells
Solution
If a given quantity of electricity liberates 0.65g of Zn2+, what amount of Hg2+ would be liberated by the same quantity of current?
[Zn = 65, Hg = 201]
A
1.00g
B
2.01g
C
4.02g
D
8.04g
medium Difficulty
Verified Correct Answer: Option B
Chemical Principles & Mechanism
At the cathode, we have:
\(Zn^{2+} + 2e^- → Zn_{(s)}\)
Normally, we need
2F → 65g
x → 0.65
x = 0.02F
Let us check how much mercury will be deposited by 0.02F of electricity
\(Hg^{2+} + 2e^-(aq) → Hg_{(s)}\)
2F → 201g
∴ 0.02F = x
x = 2.01g
Source: Myschool Past Questions Archive (Record #4057)
Chemistry
UTME / JAMB 2008
Chemical Energetics & Thermochemistry
Solution
\(NH_{3(g)} + HCl_{(g)} → NH_4Cl_{(s)}\)
The entropy change in the system above is
A
positive
B
zero
C
negative
D
indeterminate
medium Difficulty
Verified Correct Answer: Option C
Chemical Principles & Mechanism
\(NH_{3(g)} + HCl_{(g)} → NH_4Cl_{(s)}\)
Reactant = 2 moles of gaseous molecules
Product = 1 mole of gaseous molecule
Entropy change = 1 - 2 = -1 (negative)
Source: Myschool Past Questions Archive (Record #4059)
Chemistry
UTME / JAMB 2008
Chemical Energetics & Thermochemistry
Solution
Which of the following reaction is endothermic?
A
C(s) + O2(g) → CO2(g)
B
CaO(s) + H2O(l) → Ca(OH)2(s)
C
C(s) + H2O(g) → CO(g) + H2(g)
D
HCl(aq) + NaOH(aq) → NaCl(aq) + H2O(l)
medium Difficulty
Verified Correct Answer: Option C
Chemical Principles & Mechanism
Water Gas is a mixture of carbon monoxide and hydrogen produced from synthesis gas.\(H_2O + C --> H_2 + CO\) (H=+131KJ/mol)
An Endothermic process is any process which requires or absorbs thermal energy from its surroundings, usually in the form of heat.in Endothermic reaction ∆H is positive.
Therefore it is Endothermic
Source: Myschool Past Questions Archive (Record #4063)
Chemistry
UTME / JAMB 2008
Reaction Rates & Chemical Equilibrium
Solution
A catalyst speeds up the rate of chemical reaction by
A
taking part in the reaction
B
increasing the activation energy of the reaction
C
lowering the activation energy of the reaction
D
increasing the heat content
medium Difficulty
Verified Correct Answer: Option C
Chemical Principles & Mechanism
Catalyst lowers the activation energy of reaction and hence speeds up the rate of chemical reaction.
Source: Myschool Past Questions Archive (Record #4064)
Chemistry
UTME / JAMB 2008
Reaction Rates & Chemical Equilibrium
Solution
The rate of a reaction usually decreases with a decrease in the concentration of reactants because
A
kinetic energy decrease
B
temperature increase
C
speed increases
D
reactants collision decrease
medium Difficulty
Verified Correct Answer: Option D
Chemical Principles & Mechanism
Decrease in the concentration of reactants reduces the number of molecules that acquire effective collisions, and consequently reduces the reaction rate.
Source: Myschool Past Questions Archive (Record #4065)
Chemistry
UTME / JAMB 2008
Metals, Transition Elements & Extraction
Solution
The substance that is used in the steel industry for the removal of carbon, sulphur and phosphorus impurities from pig iron is
A
oxygen
B
chlorine
C
nitrogen
D
hydrogen
medium Difficulty
Verified Correct Answer: Option A
Chemical Principles & Mechanism
The substance used in the steel industry for the removal of carbon, sulphur, and phosphorus impurities from pig iron is oxygen. This process is called "oxidation" and it occurs when oxygen reacts with the impurities in the pig iron, which then form oxides that can be easily removed.
Source: Myschool Past Questions Archive (Record #4066)
Chemistry
UTME / JAMB 2008
Stoichiometry, Mole Concept & Volumetric Analysis
Solution
Which of the following compounds of trioxonitrate (V) will decompose to give dinitrogen (i) oxide and water when heated?
A
NaNO3
B
Zn(NO3)2
C
Cu(NO3)2
D
NH4NO3
medium Difficulty
Verified Correct Answer: Option D
Chemical Principles & Mechanism
\(NH_4NO_3 → N_2O + 2H_2O\)
Source: Myschool Past Questions Archive (Record #4067)
Chemistry
UTME / JAMB 2008
Organic Chemistry II: Functional Groups, Polymers & Biomolecules
Solution
When a solution of ammonium trioxocarbonate (IV) is added to a solution of an unknown salt, a white precipitate which is soluble in dilute hydrochloric acid but insoluble in ethanoic acid is formed. This indicates the presence of
A
Ca2+
B
Na+
C
Zn2+
D
K+
medium Difficulty
Verified Correct Answer: Option A
Chemical Principles & Mechanism
The test indicates the presence of \(Ca_{2+}\).
Source: Myschool Past Questions Archive (Record #4068)
Chemistry
UTME / JAMB 2008
Stoichiometry, Mole Concept & Volumetric Analysis
Solution
Leads is used for making bullets and lead shots because of its
A
resistance to corrosion
B
low melting point
C
high density
D
flexibility
medium Difficulty
Verified Correct Answer: Option C
Chemical Principles & Mechanism
Lead is used for making bullets and lead shots because of its high density.
Source: Myschool Past Questions Archive (Record #4069)
Chemistry
UTME / JAMB 2008
Stoichiometry, Mole Concept & Volumetric Analysis
Solution
which of the following gives a precipitate when treated with NaOH solution?
A
AlCl3
B
NH4Cl
C
Na2CO3
D
CH3COONa
medium Difficulty
Verified Correct Answer: Option A
Chemical Principles & Mechanism
Sodium hydroxide reacts with aluminium chloride to form a precipitate; aluminium hydroxide ; AlCl3 (Alumunium chloride).
Source: Myschool Past Questions Archive (Record #4071)
Chemistry
UTME / JAMB 2008
Metals, Transition Elements & Extraction
Solution
The most common ores of iron include
A
haematite, malachite and limonite
B
chalcocite, calamine and bornite
C
magnetite, haematite and limonite
D
magnetite, chalcocite and bornite
medium Difficulty
Verified Correct Answer: Option C
Chemical Principles & Mechanism
The most common ores of iron are magnetic, haematite and limonite
Source: Myschool Past Questions Archive (Record #4072)