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Chemistry
UTME / JAMB 1991
Oxidation, Reduction & Redox Reactions
Solution
2H2S(g) + SO2(g) → 3S(s) + 2H2O(I). The above reaction is?
A
a redox reaction H2S is the oxidant and SO2 is the reductant
B
a redox reaction in which SO2 is the oxidant and H2S is the reductant
C
not a redox reaction because there is no oxidant in reaction equation
D
not a redox because there is no reductant in the reaction equation
medium Difficulty
Verified Correct Answer: Option B
Chemical Principles & Mechanism
In the above reaction, H\(_2\)S is oxidized to H\(_2\)O while SO\(_2\) is reduced to S. Hence, H\(_2\)S is the reductant while SO\(_2\) is the oxidant.
Source: Myschool Past Questions Archive (Record #13064)
Chemistry
UTME / JAMB 1991
Reaction Rates & Chemical Equilibrium
Solution
Magnesium (IV) oxide is known to hasten the decomposition of hydrogen peroxide. Its main action is to?
A
increase the surface area of the reactants
B
increase the concntration of the reactants
C
lower the activation energy for the reaction
D
lower the heat of reaction, ∆H, for the reaction
medium Difficulty
Verified Correct Answer: Option C
Chemical Principles & Mechanism
As a catalyst, MnO2 lowers activation energy of a reaction.
Source: Myschool Past Questions Archive (Record #13069)
Chemistry
UTME / JAMB 1991
Chemical Energetics & Thermochemistry
Solution
NO(g) + CO(g) ↔ (1)/(2)N2(g) + CO2(g) ∆H = 89.3 kj.
What conditions would favour maximum conversion of nitrogen (II) oxide and carbon (II) oxide in the reaction above?
A
Low temperature and high pressure
B
High temperature and low pressure
C
High temperature and high pressure
D
Low temperature and low pressure
medium Difficulty
Verified Correct Answer: Option A
Chemical Principles & Mechanism
conditions that would favour maximum conversion of nitrogen (II) oxide and carbon (II) oxide in the reaction above?
are; i low temperature since the forward reaction is endothermic and backward reaction is exothermic.
ii high pressure since forward reaction involves a reduction in volume and backward reaction involves an increase in volume. ( reaction is in the gaseous phase).
Source: Myschool Past Questions Archive (Record #13079)
Chemistry
UTME / JAMB 1991
Stoichiometry, Mole Concept & Volumetric Analysis
Solution
Which of the following equilibria is unaffected by a pressure change?
A
2NaCI(s) ↔ 2Na (I) + CI2(g)
B
H 2(g) + I2(g) ↔ 2HI(g)
C
2O3(g) ↔ 3O2(g)
D
2NO2(g) ↔ N2O4(g)
medium Difficulty
Verified Correct Answer: Option B
Chemical Principles & Mechanism
The equilibrium concentrations of the products and reactants do not directly depend on the total pressure of the system. The only thing we consider are the gaseous substances. This means we consider the total number of gaseous substances on the reactant side and the total number of gaseous substances on the product side. The side with the lesser number of moles will be favoured by an increase in pressure because the equilibrium position will shift to that side and vice versa. However, if the number of moles of gaseous reactants is equal to the number of moles of gaseous products, pressure has no effect on equilibrium, as seen in option B only where the total number of moles gaseous reactant is 2 just as it is also for the gaseous products.
Source: Myschool Past Questions Archive (Record #13080)
Chemistry
UTME / JAMB 1991
Stoichiometry, Mole Concept & Volumetric Analysis
Which of the following gases will rekindle a brightly glowing splint?
A
NO2
B
NO
C
N2O
D
CI2
medium Difficulty
Verified Correct Answer: Option C
Chemical Principles & Mechanism
No expanded working has been attached for this question yet. The verified answer is Option C.
Source: Myschool Past Questions Archive (Record #13083)
Chemistry
UTME / JAMB 1991
Stoichiometry, Mole Concept & Volumetric Analysis
Which of the following salts can be melted without decomposition?
A
Na2CO3
B
CaCO3
C
MgCO3
D
ZnCO3
medium Difficulty
Verified Correct Answer: Option A
Chemical Principles & Mechanism
No expanded working has been attached for this question yet. The verified answer is Option A.
Source: Myschool Past Questions Archive (Record #13084)
Chemistry
UTME / JAMB 1991
Non-Metals & Their Compounds
Solution
Oxygen gas can be prepared by heating?
A
ammonium trioxonitrate (V)
B
ammonium trioxonitrate (III)
C
potassium trioxonitrate (V)
D
manganese (IV) oxide
medium Difficulty
Verified Correct Answer: Option C
Chemical Principles & Mechanism
Heating potassium trioxonitrate(V) (also known as potassium nitrate, KNO₃) can lead to the production of oxygen gas. When heated, potassium nitrate decomposes, yielding potassium nitrite (KNO₂), oxygen gas (O₂), and potentially other byproducts like nitrogen gas and potassium oxide.
Source: Myschool Past Questions Archive (Record #13085)
Chemistry
UTME / JAMB 1991
Acids, Bases, pH & Salts
Addition of aqueous ammonia to a solution of Zn++ gives a white precipitate which dissolves in an excess of ammonia because?
A
zinc is amphoteric
B
zinc hydroxide is readily soluble
C
zinc forms a complex which is readily soluble in excess ammonia
D
ammonia solution is a strong base
medium Difficulty
Verified Correct Answer: Option C
Chemical Principles & Mechanism
No expanded working has been attached for this question yet. The verified answer is Option C.
Source: Myschool Past Questions Archive (Record #13089)
Chemistry
UTME / JAMB 1991
Stoichiometry, Mole Concept & Volumetric Analysis
Which of the following, in clear solution, forms a white precipitate when carbon (IV) oxide is bubbled into it for a short time?
A
KOH
B
NaOH
C
Ca(OH)2
D
AI(OH)3
medium Difficulty
Verified Correct Answer: Option C
Chemical Principles & Mechanism
No expanded working has been attached for this question yet. The verified answer is Option C.
Source: Myschool Past Questions Archive (Record #13092)
Chemistry
UTME / JAMB 1991
Stoichiometry, Mole Concept & Volumetric Analysis
Which of the following metals can be prepared in samples by the thermal decomposition of their trioxonitrate (V) salts?
A
Copper and mercury
B
Silver and copper
C
Mercury and silver
D
Magnesium and mercury
medium Difficulty
Verified Correct Answer: Option C
Chemical Principles & Mechanism
No expanded working has been attached for this question yet. The verified answer is Option C.
Source: Myschool Past Questions Archive (Record #13094)
Chemistry
UTME / JAMB 1991
Stoichiometry, Mole Concept & Volumetric Analysis
Copper (II) tetraoxosulphate (IV) is widely used as a?
A
fertilizer
B
fungicide
C
disinfectant
D
purifier
medium Difficulty
Verified Correct Answer: Option B
Chemical Principles & Mechanism
No expanded working has been attached for this question yet. The verified answer is Option B.
Source: Myschool Past Questions Archive (Record #13095)
Chemistry
UTME / JAMB 1991
Organic Chemistry I: Hydrocarbons & Crude Oil
Which of the following compounds can exist as geometric isomers?
A
2-methylbut-2ene
B
But-2-ene
C
But-1-ene
D
CI-C-Br
medium Difficulty
Verified Correct Answer: Option B
Chemical Principles & Mechanism
No expanded working has been attached for this question yet. The verified answer is Option B.
Source: Myschool Past Questions Archive (Record #13096)
Chemistry
UTME / JAMB 1991
Stoichiometry, Mole Concept & Volumetric Analysis
Solution
How many grams of bromine will be required to completely react with 10 g of propyne?
(C = 12, H = 1, Br = 80)
A
20 g
B
40 g
C
60 g
D
80 g
medium Difficulty
Verified Correct Answer: Option D
Chemical Principles & Mechanism
Firstly, you must get the correct chemical equation for the reaction, if not, you will get the answer wrong.
Possible equations are:
Br\(_2\) + C\(_3\)H\(_4\) → C\(_3\)H\(_4\)Br\(_2\) - This equation is wrong, so don't fall for this.
2Br\(_2\) + C\(_3\)H\(_4\) → CH\(_3\)CBr\(_2\)CHBr\(_2\) - This is the correct equation because the reaction is an electrophylic addition reaction, where the bromine molecules add to the triple bond in propyne.When propyne reacts with bromine, the primary product formed is 1,1,2,2-tetrabromopropane; this reaction causes the reddish-brown colour of bromine to disappear as the bromine is added across the triple bond of propyne, resulting in a colorless product.
2Br\(_2\) + C\(_3\)H\(_4\) → CH\(_3\)CBr\(_2\)CHBr\(_2\)
(4 X 80)g (36 + 4)g
320 g of C\(_3\)H\(_4\) reacts with 40 g of Br
X g will react with 10g of C\(_3\)H\(_4\)
(10)/(40) x (320) /(1) = 80g
If you apply the first equation, you would obtain option B (40g) which is wrong. However, the reaction of Bromine with propyne would yield 1,1,2,2- tetrabromopropane not 1,2- dibromopropene.
Source: Myschool Past Questions Archive (Record #13100)
Chemistry
UTME / JAMB 1991
Organic Chemistry I: Hydrocarbons & Crude Oil
Ethene when passed into concentrated H2SO4 is rapidly absorbed. The product is diluted with water and then warmed to produce?
A
ethanol
B
diethyl ether
C
ethanal
D
diethyl sulphate
medium Difficulty
Verified Correct Answer: Option A
Chemical Principles & Mechanism
No expanded working has been attached for this question yet. The verified answer is Option A.
Source: Myschool Past Questions Archive (Record #13102)
Chemistry
UTME / JAMB 1991
Organic Chemistry II: Functional Groups, Polymers & Biomolecules
One advantages of detergents over soap is that detergents?
A
are easier to maufacture
B
foam more than soap
C
form soluble salts with hard water
D
are able to deter germs more than soap
medium Difficulty
Verified Correct Answer: Option C
Chemical Principles & Mechanism
No expanded working has been attached for this question yet. The verified answer is Option C.
Source: Myschool Past Questions Archive (Record #13104)