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Chemistry
UTME / JAMB 2024
Stoichiometry & Mole Concept
Solution
The Van der waals forces of attraction operates between
A
atoms
B
cations
C
molecules
D
anions
medium Difficulty
Verified Correct Answer: Option C
Chemical Principles & Mechanism
Van der Waals forces of attraction operate between molecules that are very close together. They can occur between polar molecules with permanent dipoles and non-polar molecules, or between molecules with permanent dipoles and molecules without permanent dipoles.
Source: Myschool Past Questions Archive (Record #70398)
Chemistry
UTME / JAMB 2024
Atomic Structure and Periodic Table
Solution
The electronic configuration of an atom of Nitrogen is 1s\(^2\) 2s\(^2\) 2p\(^1_x\) 2p\(^1_y\) 2p\(^1_z\) because the atom is
A
in an excited state
B
undergoing energy changes
C
unstable and ready to combine with another
D
simply obeying rules governing electron configuration
medium Difficulty
Verified Correct Answer: Option D
Chemical Principles & Mechanism
The rules governing electron configuration are the Aufbau principle, Pauli's exclusion principle, and Hund's rule:
Aufbau principle: Electrons fill the lowest energy orbitals first.
Pauli's exclusion principle: No two electrons can have the same spin in one orbital. Each orbital can hold a maximum of two electrons with opposite spins.
Hund's rule: Electrons fill empty orbitals singly before pairing up in the same sub-levels.
Source: Myschool Past Questions Archive (Record #70399)
Chemistry
UTME / JAMB 2024
Atomic Structure and Periodic Table
Solution
The reaction of hydrogen and chlorine to produce hydrogen chloride gas is explosive in
A
diffused light
B
sunlight
C
infrared light
D
Raman light
medium Difficulty
Verified Correct Answer: Option B
Chemical Principles & Mechanism
In direct sunlight, the formed product hydrogen chloride gets protonated which results in an explosion. This reaction is a free radical substitution reaction.
Source: Myschool Past Questions Archive (Record #70400)
Chemistry
UTME / JAMB 2024
Acids, Bases, and Salts
Solution
The term strong and weak acids is used to indicate the
A
number of H\(^+\) released by an acid
B
number of OH\(^-\) released by an acid
C
extent of ionization of an acid
D
strength of its action on substance
medium Difficulty
Verified Correct Answer: Option C
Chemical Principles & Mechanism
The terms "strong" and "weak" are used to describe the extent to which an acid dissociates into ions in an aqueous solution.
Strong acid: An acid that completely dissociates into ions in water. For example, hydrogen chloride (HCl) is a strong acid because it ionizes completely into hydrogen ions and chloride ions in water.
Weak acid: An acid that only slightly dissociates into ions in water. For example, acetic acid is a weak acid because it only dissociates about 5% into ions in water
Source: Myschool Past Questions Archive (Record #70401)
Chemistry
UTME / JAMB 2024
Matter & Separation Techniques
Solution
The main constituent of water-glass is
A
calcium trioxosilicate(IV)
B
calcium trioxosulphate(IV)
C
sodium trioxosulphate(IV)
D
sodium trioxosilicate(IV)
medium Difficulty
Verified Correct Answer: Option D
Chemical Principles & Mechanism
Water glass, also known as sodium silicate or alkali silicate glass, is a glassy solid made up of sodium oxide (Na\(_2\)O) and silica (silicon dioxide, SiO\(_2\)).
Source: Myschool Past Questions Archive (Record #70402)
Chemistry
UTME / JAMB 2024
Matter & Separation Techniques
Solution
Which of the following represents an order of increasing reactivity?
A
Au < Cu < Sn < Fe < Ca
B
Ca < Fe < Sn < Cu < Au
C
Au < Cu < Fe < Sn < Ca
D
Ca < Sn < Fe < Cu < Au
medium Difficulty
Verified Correct Answer: Option A
Chemical Principles & Mechanism
The order of reactivity of metals, from most to least reactive, is:
Potassium: Most reactive and easily forms positive ions
Sodium: Second most reactive
Lithium: Third most reactive
Calcium: Fourth most reactive
Magnesium: Fifth most reactive
Aluminum: Sixth most reactive
Zinc: Seventh most reactive
Iron: Eighth most reactive
Tin: Ninth most reactive
Lead: Tenth most reactive
Hydrogen: Eleventh most reactive
Copper: Twelfth most reactive
Silver: Thirteenth most reactive
Gold: fourteenth most reactive
Platinum: Fifteenth most reactive
Source: Myschool Past Questions Archive (Record #70403)
Chemistry
UTME / JAMB 2024
Matter & Separation Techniques
Solution
An oxide of nitrogen that can rekindle a glowing splint is
A
nitrogen(I)oxide
B
nitrogen(II)oxide
C
nitrogen(IV)oxide
D
dinitrogen tetraoxide
medium Difficulty
Verified Correct Answer: Option A
Chemical Principles & Mechanism
Nitrogen(I)oxide (nitric oxide) rekindles a brightly glowing splint just like oxygen does. This similarity is because both nitric oxide and oxygen support combustion.
Source: Myschool Past Questions Archive (Record #70412)
Chemistry
UTME / JAMB 2024
Acids, Bases, and Salts
Solution
In a chemical reaction, surface area of reactants can affect
A
CaCO\(_3\) + 2HCl → CaCl\(_2\) + H\(_2\)O + CO\(_2\)
B
MgCl\(_2\) + H\(_2\)SO\(_4\) → MgSO\(_4\) + 2HCl
C
H\(_2\) + Cl\(_2\) → 2HCl
D
NaOH + HCl → NaCl + H\(_2\)O
medium Difficulty
Verified Correct Answer: Option A
Chemical Principles & Mechanism
The surface area of reactants affects the rate of a reaction between limestone and hydrochloric acid because it increases the number of collisions between the particles of the reactants. For example, if you have a large marble chip of calcium carbonate and hydrochloric acid, the acid can't reach all the calcium carbonate in the middle of the chip. If you break the marble chip into smaller pieces, you'll have a larger surface area for the acid to react with, and the reaction will happen faster.
Source: Myschool Past Questions Archive (Record #70416)
Chemistry
UTME / JAMB 2024
Stoichiometry & Mole Concept
Solution
C\(_2\)H\(_{4(g)}\) + 3O\(_{2(g)}\) → 2CO\(_{2(g)}\) + 2H\(_2\)O\(_{(g)}\)
The above equation represents the combustion of ethene.If 10cm\(^3\) of ethene is burnt in 50cm\(^3\) of oxygen, what would be the volume of oxygen that would remain at the end of the reaction?
A
20cm\(^3\)
B
40cm\(^3\)
C
60cm\(^3\)
D
50cm\(^3\)
medium Difficulty
Verified Correct Answer: Option A
Chemical Principles & Mechanism
Gay Lussac’s Law of Combining Volumes states that when gases react, they do so in volumes which bear a simple ratio to one another, and to the volume of the product(s) formed if gaseous, provided the temperature and pressure remain constant.
C\(_2\)H\(_{4(g)}\) + 3O\(_{2(g)}\) → 2CO\(_{2(g)}\) + 2H\(_2\)O\(_{(g)}\)
1 mole : 3 moles
Total volume required: 10 cm\(^3\) 50 cm\(^3\)
Reacted Volume: 10 cm\(^3\) 30 cm\(^3\)
Residual volume: 0 (50 - 30) = 20 cm\(^3\)
Source: Myschool Past Questions Archive (Record #70417)
Chemistry
UTME / JAMB 2024
Atomic Structure and Periodic Table
Solution
The hybridization scheme in ethyne is
A
sp
B
sp\(^3\)
C
sp\(^2\)d
D
sp\(^2\)s
medium Difficulty
Verified Correct Answer: Option A
Chemical Principles & Mechanism
The hybridization scheme in ethyne is sp. In ethyne, each carbon atom's 2s orbital combines with one of its 2p orbitals to form two sp hybrid orbitals. The frontal lobes of these orbitals face away from each other, resulting in a straight line.
Source: Myschool Past Questions Archive (Record #70418)
Chemistry
UTME / JAMB 2024
Atomic Structure and Periodic Table
Solution
An organic compound with general formula RCOR' is an
A
alkanone
B
alkanal
C
alkanoate
D
alkanoic acid
medium Difficulty
Verified Correct Answer: Option A
Chemical Principles & Mechanism
An organic compound with the general formula RCOR' is an alkanone, which is a type of ketone.
Ketones: Have the general formula RCOR' and contain a carbonyl group, which is a carbon atom double-bonded to an oxygen atom.
Source: Myschool Past Questions Archive (Record #70419)
Chemistry
UTME / JAMB 2024
Stoichiometry & Mole Concept
Solution
The amount of Faraday required to discharge 4.5 moles of Al\(^{3+}\) is
A
13.5
B
4.5
C
7.5
D
1.5
medium Difficulty
Verified Correct Answer: Option A
Chemical Principles & Mechanism
Firstly, Al\(^{3+}\) + 3e\(^-\) → Al
1 mole of Al = 1F X 3e\(^-\)
1mole = 3F
4.5moles = X
X = 4.5 X 3 = 13.5 F
Source: Myschool Past Questions Archive (Record #70420)
Chemistry
UTME / JAMB 2024
Acids, Bases, and Salts
Solution
The reaction between alkanoic acids and alkanols in the presence of an acid catalyst is known as
A
saponification
B
dehydration
C
esterification
D
hydrolysis
medium Difficulty
Verified Correct Answer: Option C
Chemical Principles & Mechanism
The reaction between alkanoic acids and alkanols in the presence of an acid catalyst is called esterification:
Esterification is a chemical reaction that combines an alcohol (ROH) and an organic acid (RCOOH) to form an ester (RCOOR) and water. The reaction can be catalyzed by an acid or a base.
Source: Myschool Past Questions Archive (Record #70421)
Chemistry
UTME / JAMB 2024
Matter & Separation Techniques
Solution
C\(_x\)H\(_y\)O + 5O\(_2\) → 4CO\(_2\) + 4H\(_2\)O
C\(_x\)H\(_y\)O in the equation is
A
CH\(_2\)O
B
C\(_2\)H\(_6\)O
C
CH\(_4\)O
D
C\(_2\)H\(_4\)O
medium Difficulty
Verified Correct Answer: Option D
Chemical Principles & Mechanism
C\(_x\)H\(_y\)O + 5O\(_2\) → 4CO\(_2\) + 4H\(_2\)O
On balancing the equation, we should have
X = 4 , y = 8 and O = 2 ⇒ C\(_4\)H\(_8\)O\(_2\)
Since 2 is a common factor to the three atoms, we can divide through by 2, considering the fact that that formula is not in the option.
We finally have C\(_2\)H\(_4\)O
Source: Myschool Past Questions Archive (Record #70429)
Chemistry
UTME / JAMB 2024
Acids, Bases, and Salts
Solution
Alkylation of benzene is catalyzed by
A
palladium
B
nickel
C
sunlight
D
aluminium chloride
medium Difficulty
Verified Correct Answer: Option D
Chemical Principles & Mechanism
Alkylation is the process of substituting an alkyl group into a benzene ring, replacing a hydrogen on the ring with a group like methyl or ethyl.
Alkylation of benzene can be catalyzed by a number of substances, including:
Aluminum chloride: A common catalyst for the Friedel-Crafts alkylation of benzene. Aluminum chloride acts as a Lewis acid, coordinating with halogens to generate an electrophile.
Fluorinated alumina: Catalyzes the alkylation of benzene with propylene.
Methyl- and ethylsilanes: Catalyze the alkylation of benzene with ethylene and propylene.
Acidic zeolite catalysts: Such as mordenite, which can be used to alkylate benzene with 1-dodecene.
Boron trifluoride: Catalyzes the alkylation of benzene with 2-propanol, forming a carbocation intermediate that attaches to the benzene ring
Source: Myschool Past Questions Archive (Record #70432)