The effect of the presence of impurities such as carbon and sulphur on iron is that they

A. give it high tensile strenght

B. make it malleable and ductile

Which of the following statements is true about 2-methylpropane and butane

D. They have the same chemical properties

A. They are not members of the same homologous series

B. They have the same boiling point

C. They have different number of carbon atoms

D. They have the same chemical properties

Hardness of water is mainly due to the presence of

B. calcium trioxocarbonate (IV) or calcium tetraoxosulphate (VI)

A. calcium hydroxide or magnesium hydroxide

B. calcium trioxocarbonate (IV) or calcium tetraoxosulphate (VI)

C. sodium hydroxide or magnesium hydroxide

D. calcium chloride or sodium chloride salts

N2O4(g) ↔ 2NO2(g) ΔH = +ve In the reaction above, an increase in temperature will

A. increase the value of the equilibrium constant

B. decreases the value of the equilibrium constant

C. increase in the reactant production

D. shift the equilibrium to the left

The condition required for corrosion to take place is the presence of

B. water, carbon (IV) oxide and oxygen

C. oxygen and carbon (IV) oxide

The function of zinc electrode in a galvanic cells is that it

B. serves as the positive electrode

An effect of thermal pollution on water bodies is that the

B. volume of chemical waste increase

C. level of oxides of nitrogen increase

The principle of column chromatography is based on the ability of the constituents to

A. move at different speeds in the column

B. dissolve in each other in the column

C. react with the solvent in the column

D. react with each other in the column

Bronze is preferred to copper in the making of medals because it

B. can withstand low temperature

Which of the following properties is NOT peculiar to matter?

D. Random motion of particles increases from gas to solid

A. kinetic energy of particles increase from solid to gas

B. Random motion of particles increases from liquid to gas

C. Orderliness of particles increases from gas to liquid

D. Random motion of particles increases from gas to solid

The importance of sodium aluminate (III) in the treatment of water is to

C. prevent goitre and tooth decay

Which of the following questions is correct about the periodic table?

B. The valence electrons of the elements increase progressively across the period

A. The non-metallic properties of the elements tend to decrease across each period

B. The valence electrons of the elements increase progressively across the period

C. Elements in the same group have the same numbeer of electron shells

D. Elements in the same period have the number of valence electrons

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JAMB 2011

2011 JAMB Chemistry Past Questions

The 2011 JAMB Chemistry past questions with answers: 47 objective questions from the 2011 paper in the DeeepSolve question bank, each with its answer behind "Show answer". Try each question before you check, then practise the paper as a timed JAMB-style CBT.

Practise this paper as a timed JAMB-style CBT All JAMB Chemistry years

Questions

1.
The effect of the presence of impurities such as carbon and sulphur on iron is that they
1. A.give it high tensile strenght
2. B.make it malleable and ductile
3. C.increase its melting point
4. D.lower its melting point
Show answer
Answer: D. lower its melting point
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2.
Given that M is the mass of a substance deposited during electrolysis and Q is the quantity of electricity consumed, then Faraday's first law can be written as [Electrochemical equivalent]
1. A.M = E/Q
2. B.M = EQ
3. C.M = Q/E
4. D.M = E/2Q
Show answer
Answer: B. M = EQ
AI explanation
Analysis
The question asks for the mathematical expression of Faraday’s First Law of Electrolysis, which relates the mass of a substance deposited at an electrode to the quantity of electricity passed through the electrolyte.
Concept Explanation
Faraday’s First Law of Electrolysis states that the mass ( $M$ ) of a substance deposited or liberated during electrolysis is directly proportional to the quantity of electricity ( $Q$ ) passed through the electrolyte.
Mathematically, this is expressed as: $M \propto Q$
To remove the proportionality sign, we introduce a constant of proportionality, $Z$ , which represents the electrochemical equivalent of the substance. $M = ZQ$
In the context of this specific question, the symbol E is used to represent the electrochemical equivalent. Therefore, the formula becomes: $M = EQ$
Step-by-Step Solution
Identify the variables: • $M$ = Mass of the substance deposited. • $Q$ = Quantity of electricity. • $E$ = Electrochemical equivalent.
Apply the Law: According to Faraday's first law, the mass deposited is the product of the electrochemical equivalent and the quantity of electricity.
Formulate the equation: $M = E \times Q$ or $M = EQ$ .
Conclusion
Comparing our derived formula ( $M = EQ$ ) with the given options:
Option A: $M = E/Q$ (Incorrect)
Option B: $M = EQ$ (Correct)
Option C: $M = Q/E$ (Incorrect)
Option D: $M = E/2Q$ (Incorrect)
Exam Tip
Remember the mnemonic "MEQ" (like "Make" or "Me Q"). If you ever forget the formula, just remember that the mass ( $M$ ) increases as you increase the quantity of electricity ( $Q$ ), so they must be multiplied by the constant ( $E$ ), not divided.
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3.
Which of the following statements is true about 2-methylpropane and butane
1. A.They are not members of the same homologous series
2. B.They have the same boiling point
3. C.They have different number of carbon atoms
4. D.They have the same chemical properties
Show answer
Answer: D. They have the same chemical properties
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4.
The constituents of baking powder that makes the dough to rise is
1. A.NaHCO3
2. B.NaOH
3. C.Na2CO3
4. D.NaCl
Show answer
Answer: A. NaHCO3
AI explanation
Analysis
The question asks for the specific chemical compound present in baking powder that is responsible for the rising of dough during baking.
Concept Explanation
Baking powder is a chemical leavening agent. It consists of a base (usually sodium bicarbonate) and an acid (or an acidic salt). When baking powder is moistened and heated, a chemical reaction occurs between the base and the acid, releasing carbon dioxide ( $CO_2$ ) gas.
The chemical reaction for the decomposition of sodium bicarbonate (baking soda) when heated is:
$2NaHCO_3(s) \rightarrow Na_2CO_3(s) + H_2O(g) + CO_2(g)$
The bubbles of carbon dioxide gas become trapped in the dough, causing it to expand or "rise," which gives cakes and bread their light, airy texture.
Step-by-Step Solution
Evaluate the options: • A. $NaHCO_3$ (Sodium hydrogen carbonate/Sodium bicarbonate): This is the active ingredient in baking powder that releases $CO_2$ upon heating. • B. $NaOH$ (Sodium hydroxide): This is a strong caustic base (caustic soda) and is not used in baking. • C. $Na_2CO_3$ (Sodium carbonate): This is a product of the decomposition of baking soda, but it is not the primary ingredient used to initiate the rising process. • D. $NaCl$ (Sodium chloride): This is common table salt, used for flavor, not for leavening.
Conclusion: Sodium hydrogen carbonate ( $NaHCO_3$ ) is the essential constituent that undergoes thermal decomposition to produce the gas necessary for the dough to rise.
Exam Tip
When you see questions about "rising" in baking, always look for carbonates or bicarbonates. Remember that $NaHCO_3$ is "Baking Soda," and when mixed with an acid, it creates the perfect environment for gas production.
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5.
The ability of carbon to form long chains is referred to as
1. A.alkylation
2. B.acylation
3. C.catenation
4. D.carbonation
Show answer
Answer: C. catenation
AI explanation
Analysis
The question asks for the specific chemical term used to describe the unique property of carbon atoms to bond with other carbon atoms to form long, stable chains or rings.
Concept Explanation
Carbon is unique in the periodic table because of its electronic configuration ( $1s^2 2s^2 2p^2$ ). It has four valence electrons, allowing it to form four strong covalent bonds. Because the Carbon-Carbon (C-C) bond is exceptionally strong and stable, carbon atoms can link together in an almost infinite variety of ways—straight chains, branched chains, or closed rings. This property is the fundamental reason why there are millions of organic compounds in existence.
In chemistry, the term for the self-linking property of an element to form chains of its own atoms is catenation. While other elements like silicon or sulfur can show some degree of catenation, carbon exhibits this property to the greatest extent.
Step-by-Step Breakdown
Analyze the options: • Alkylation: This is a chemical process where an alkyl group is transferred from one molecule to another. • Acylation: This is the process of adding an acyl group to a compound. • Catenation: This is the specific term defined as the ability of an element to form covalent bonds with other atoms of the same element to form long chains or structures. • Carbonation: This usually refers to the process of dissolving carbon dioxide in a liquid (like in soft drinks).
Conclusion: Since the question specifically describes the formation of long chains by carbon, "catenation" is the correct scientific term.
Final Answer
The correct option is C.
Exam Tip: Remember that "catenation" comes from the Latin word catena, which means "chain." Whenever you see a question about carbon forming chains, think of a "chain" (catenation).
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6.
Hardness of water is mainly due to the presence of
1. A.calcium hydroxide or magnesium hydroxide
2. B.calcium trioxocarbonate (IV) or calcium tetraoxosulphate (VI)
3. C.sodium hydroxide or magnesium hydroxide
4. D.calcium chloride or sodium chloride salts
Show answer
Answer: B. calcium trioxocarbonate (IV) or calcium tetraoxosulphate (VI)
AI explanation
1. Analyze the Question
The question asks for the chemical compounds responsible for the "hardness" of water. Water hardness refers to the presence of specific dissolved mineral salts, primarily those of calcium and magnesium, which prevent soap from lathering easily.
2. Explain the Concept
Water hardness is categorized into two types:
Temporary Hardness: Caused by the presence of calcium hydrogentrioxocarbonate (IV) or magnesium hydrogentrioxocarbonate (IV). This can be removed by boiling.
Permanent Hardness: Caused by the presence of dissolved calcium or magnesium salts, specifically calcium tetraoxosulphate (VI) (calcium sulphate) or calcium chloride. These salts do not precipitate out by boiling.
In chemistry, "trioxocarbonate (IV)" is the IUPAC name for carbonate ( $CO_3^{2-}$ ), and "tetraoxosulphate (VI)" is the IUPAC name for sulphate ( $SO_4^{2-}$ ).
3. Show the Solution
Option A: Calcium hydroxide and magnesium hydroxide are generally insoluble in water and are not the primary causes of water hardness.
Option B: Calcium trioxocarbonate (IV) ( $CaCO_3$ ) and calcium tetraoxosulphate (VI) ( $CaSO_4$ ) are classic examples of salts that contribute to the hardness of water. While $CaCO_3$ is often associated with temporary hardness (in the form of hydrogentrioxocarbonate), these salts are the standard culprits identified in chemistry curricula for water hardness.
Option C: Sodium hydroxide is a strong base and does not cause water hardness.
Option D: While calcium chloride causes hardness, sodium chloride (common salt) does not cause water hardness. Therefore, this option is incorrect.
Comparing the options, Option B contains the salts most accurately associated with the mineral content that makes water "hard."
4. Identify the Answer
The correct option is B.
5. Exam Tip
When you see "trioxocarbonate (IV)" or "tetraoxosulphate (VI)" in an exam, don't panic! Just remember:
Trioxocarbonate (IV) = Carbonate ( $CO_3$ )
Tetraoxosulphate (VI) = Sulphate ( $SO_4$ )
Memory Trick: Hard water is "heavy" with minerals. Think of Calcium and Magnesium as the "Hard" guys. If you see them paired with Sulphate or Carbonate, that's your answer!
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7.
N2O4(g) ↔ 2NO2(g) ΔH = +ve In the reaction above, an increase in temperature will
1. A.increase the value of the equilibrium constant
2. B.decreases the value of the equilibrium constant
3. C.increase in the reactant production
4. D.shift the equilibrium to the left
Show answer
Answer: A. increase the value of the equilibrium constant
AI explanation
Analysis of the Question
This question tests your understanding of Le Chatelier’s Principle and how temperature changes affect the equilibrium constant ( $K$ ) of a reversible reaction.
Concept Explanation
Le Chatelier’s Principle states that if a dynamic equilibrium is disturbed by changing the conditions (like temperature, pressure, or concentration), the position of equilibrium shifts to counteract the change.
Endothermic Reactions ( $\Delta H = +ve$ ): These reactions absorb heat. You can think of heat as a "reactant." • Equation: $\text{Heat} + N_2O_4(g) \rightleftharpoons 2NO_2(g)$
Effect of Temperature: • When you increase the temperature of an endothermic reaction, the system tries to use up the extra heat by shifting the equilibrium to the right (towards the products). • Because the concentration of products ( $[NO_2]$ ) increases and the concentration of reactants ( $[N_2O_4]$ ) decreases, the equilibrium constant ( $K$ ) increases.
Step-by-Step Solution
Identify the reaction type: The value $\Delta H = +ve$ indicates that the forward reaction is endothermic.
Apply the temperature change: Increasing the temperature adds heat to the system.
Predict the shift: According to Le Chatelier’s Principle, the system will shift to the right to consume the added heat.
Determine the effect on $K$ : For endothermic reactions, an increase in temperature favors the forward reaction, leading to a higher concentration of products relative to reactants. Since $K = \frac{[\text{Products}]}{[\text{Reactants}]}$ , an increase in the numerator and a decrease in the denominator results in a larger value for $K$ .
Evaluating the Options
A. Increase the value of the equilibrium constant: This is correct because the forward reaction is favored in an endothermic process when temperature rises.
B. Decreases the value of the equilibrium constant: This would only happen if the reaction were exothermic ( $\Delta H = -ve$ ).
C. Increase in the reactant production: Incorrect; the equilibrium shifts to the right, producing more $NO_2$ (product), not reactants.
D. Shift the equilibrium to the left: Incorrect; the equilibrium shifts to the right to absorb the excess heat.
Exam Tip
Remember the "Temperature-K Rule":
Endothermic ( $\Delta H > 0$ ): Temperature $\uparrow \implies K \uparrow$
Exothermic ( $\Delta H < 0$ ): Temperature $\uparrow \implies K \downarrow$ A simple way to remember this is that in endothermic reactions, heat is a "friend" to the products, so adding more heat helps the reaction move forward!
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8.This question needs a diagram, table or passage that we don't have yet, so it isn't shown.
9.
Which of the following noble gases is commonly found in the atmosphere?
1. A.Xenon
2. B.Neon
3. C.Helium
4. D.Argon
Show answer
Answer: D. Argon
AI explanation
Analysis
The question asks for the noble gas that is most abundant and commonly found in the Earth's atmosphere.
Concept
Noble gases (Group 18 elements) are chemically inert due to their stable octet configuration. While they are all present in the atmosphere in trace amounts, their concentrations vary significantly:
Argon (Ar): Makes up approximately 0.93% of the Earth's atmosphere by volume. It is the third most abundant gas in the atmosphere after Nitrogen and Oxygen.
Neon (Ne): Present in very small trace amounts (approx. 0.0018%).
Helium (He): Present in even smaller trace amounts (approx. 0.0005%).
Xenon (Xe): Present in extremely minute trace amounts (approx. 0.000008%).
Solution
Identify the composition of air: The atmosphere is primarily composed of Nitrogen (~78%) and Oxygen (~21%).
Locate the noble gases: Among the noble gases, Argon is the only one present in a significant percentage (nearly 1%).
Evaluate the options: Because Argon constitutes nearly 1% of the air we breathe, it is the most "common" noble gas found in the atmosphere. The others are present in such small quantities that they are considered rare gases.
Conclusion
Based on the atmospheric composition, Argon is the most abundant noble gas in the atmosphere.
Exam Tip: Remember the acronym "N-O-A" for the most abundant gases in the atmosphere: Nitrogen, Oxygen, and Argon. This will help you quickly identify Argon as the most common noble gas in any exam setting.
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10.
The bleaching action of chlorine gas is effective due to the presence of
1. A.hydrogen chloride
2. B.water
3. C.air
4. D.oxygen
Show answer
Answer: B. water
AI explanation
Analysis of the Question
This question tests your understanding of the chemical properties of chlorine gas, specifically its role as a bleaching agent. You are asked to identify the substance that must be present for chlorine to perform its bleaching function.
Concept Explanation
Chlorine ( $Cl_2$ ) acts as a bleaching agent through an oxidation reaction. However, dry chlorine gas does not bleach. For chlorine to bleach, it must react with water to form two acids: hydrochloric acid ( $HCl$ ) and hypochlorous acid ( $HOCl$ ).
The chemical equation for this reaction is:
$Cl_2(g) + H_2O(l) \rightleftharpoons HCl(aq) + HOCl(aq)$
The hypochlorous acid ( $HOCl$ ) formed is unstable and readily decomposes to release nascent oxygen (a single atom of oxygen, $[O]$ ), which is a very powerful oxidizing agent:
$HOCl(aq) \rightarrow HCl(aq) + [O]$
The nascent oxygen then reacts with the colored pigments in the material (like dyes or fabrics) to oxidize them into colorless substances. Therefore, without water, the hypochlorous acid cannot be formed, and the bleaching process cannot occur.
Step-by-Step Solution
Identify the bleaching agent: Chlorine gas ( $Cl_2$ ) is the primary agent, but it requires a medium to react.
Examine the reaction: Chlorine reacts with water to produce hypochlorous acid ( $HOCl$ ).
Determine the active component: The hypochlorous acid releases nascent oxygen, which is responsible for the actual bleaching (removal of color).
Conclusion: Since the entire process starts with the reaction between chlorine and water, water is the essential component required for the bleaching action to take place.
Identification of the Answer
Comparing this to the provided options:
A. Hydrogen chloride is a product of the reaction, not the cause of bleaching.
B. Water is the essential reactant that enables the formation of the bleaching agent.
C. Air is not required for this specific chemical reaction.
D. Oxygen is the byproduct of the decomposition of $HOCl$ , but it is the water that initiates the process.
Exam Tip
Always remember: "Dry chlorine does not bleach." If you see a question about chlorine bleaching, immediately look for "water" or "moisture" as the key requirement. If the question asks about the substance responsible for the bleaching, it is "nascent oxygen," but if it asks what must be present for the action to be effective, it is "water."
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11.This question needs a diagram, table or passage that we don't have yet, so it isn't shown.
12.
CH4(g) + Cl2(g) → CH3 Cl(s) + HCl(g) The major factor that influence the rate of the reaction above is
1. A.catalyst
2. B.temperature
3. C.concentration
4. D.light
Show answer
Answer: D. light
AI explanation
1. Analyze the question
The reaction provided is: CH₄(g) + Cl₂(g) → CH₃Cl(g) + HCl(g)
This is a classic example of a free-radical substitution reaction (specifically, the halogenation of an alkane). You are asked to identify the major factor that influences the rate of this specific reaction.
2. Explain the concept
In organic chemistry, alkanes like methane (CH₄) are generally unreactive under normal conditions. For methane to react with chlorine (Cl₂), the chlorine molecule must first undergo homolytic fission (splitting into two chlorine radicals, Cl•).
This process requires energy to break the Cl-Cl bond. In this specific reaction, this energy is provided by ultraviolet (UV) light or sunlight. Without this energy source, the reaction will not proceed at any significant rate at room temperature.
3. Show the solution
Step 1: Identify the reaction type. This is a photochemical reaction.
Step 2: Understand the mechanism. The reaction proceeds via a free-radical chain mechanism: • Initiation: Cl₂ + hv (light) → 2Cl• • Propagation: CH₄ + Cl• → CH₃• + HCl, then CH₃• + Cl₂ → CH₃Cl + Cl•
Step 3: Evaluate the options. • Catalyst: While catalysts speed up reactions, they are not the primary requirement for initiating this specific photochemical process. • Temperature: While temperature affects reaction rates, it is not the major factor that triggers this specific substitution reaction. • Concentration: Changing concentration affects the rate of many reactions, but it won't initiate this one without the presence of light. • Light: The reaction is photochemical. The presence of UV light is essential to provide the activation energy needed to break the chlorine bond and start the chain reaction.
4. Identify the answer
The major factor that influences the rate of this reaction is light. Therefore, the correct option is D.
5. Tip for your exam
Whenever you see a reaction involving an alkane and a halogen (like Cl₂ or Br₂) in your JAMB or WASSCE questions, look for keywords like "UV light," "sunlight," or the symbol hv (which represents a photon of light). These reactions are almost always photochemical, and "light" is the key factor.
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13.
CH3COOH(aq) + OH-(aq) ↔ CH3COO-(aq) + H2O(l) In the reaction above ,CH3COO-(aq) is
1. A.conjugate base
2. B.acid
3. C.base
4. D.conjugate acid
Show answer
Answer: A. conjugate base
AI explanation
Analysis
This question tests your understanding of the Brønsted-Lowry Theory of Acids and Bases. According to this theory, an acid is a proton ( $H^+$ ) donor, and a base is a proton acceptor. When an acid loses a proton, it forms a conjugate base. When a base gains a proton, it forms a conjugate acid.
Concept Explanation
In any acid-base reaction, we look at the relationship between the reactants and the products:
The Acid: $CH_3COOH$ (ethanoic acid) donates a proton ( $H^+$ ) to the $OH^-$ ion.
The Base: $OH^-$ (hydroxide ion) accepts the proton.
The Conjugate Base: After $CH_3COOH$ loses its proton, it becomes $CH_3COO^-$ (ethanoate ion). Because it is the species left behind after the acid has donated its proton, it is called the conjugate base.
The Conjugate Acid: After $OH^-$ accepts the proton, it becomes $H_2O$ . Because it is the species formed after the base has accepted a proton, it is called the conjugate acid.
Step-by-Step Solution
Step 1: Identify the reactant that loses the proton. $CH_3COOH \rightarrow CH_3COO^- + H^+$ . Since $CH_3COOH$ is the acid, the resulting $CH_3COO^-$ is its conjugate base.
Step 2: Identify the reactant that gains the proton. $OH^- + H^+ \rightarrow H_2O$ . Since $OH^-$ is the base, the resulting $H_2O$ is its conjugate acid.
Step 3: Match the species in the question. The question asks for the identity of $CH_3COO^-$ . Based on our analysis, it is the conjugate base of $CH_3COOH$ .
Conclusion
Exam Tip
Remember the "minus one" rule: A conjugate base is always what remains of an acid after it has lost one $H^+$ . If you are ever confused, just look at the pair: the one with one less hydrogen is the conjugate base!
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14.
Which of the following compounds will undergo polymerization reaction?
1. A.C2H4
2. B.C2H5COOH
3. C.C2H6
4. D.C2H5OH
Show answer
Answer: A. C2H4
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15.
An isotope has an atomic number of 15 and a mass number of 31. The number of protons it contain is
1. A.16
2. B.15
3. C.46
4. D.31
Show answer
Answer: B. 15
AI explanation
Analysis
The question asks for the number of protons in an atom given its atomic number and mass number.
Concept Explanation
To solve this, you need to understand the fundamental definitions of atomic structure:
Atomic Number ( $Z$ ): This represents the number of protons in the nucleus of an atom. It is the identity of the element (e.g., Phosphorus has an atomic number of 15).
Mass Number ( $A$ ): This is the sum of the number of protons and the number of neutrons in the nucleus ( $A = \text{protons} + \text{neutrons}$ ).
Neutral Atom: In a neutral atom, the number of protons is equal to the number of electrons.
Step-by-Step Solution
Step 1: Identify the given values from the question. • Atomic number ( $Z$ ) = 15 • Mass number ( $A$ ) = 31
Step 2: Apply the definition of atomic number. • By definition, the atomic number is exactly equal to the number of protons. • Therefore, Number of protons = Atomic number = 15.
Step 3: (Optional) Calculate neutrons for extra practice. • Neutrons = Mass number - Atomic number • Neutrons = 31 - 15 = 16.
Since the question specifically asks for the number of protons, we look at the atomic number provided.
Conclusion
The number of protons is 15. Looking at the options provided, this corresponds to option B.
Exam Tip
Always remember the acronym "APE":
Atomic number = Protons = Electrons (in a neutral atom). If you are ever confused, just look for the atomic number—it is the "ID card" of the element and tells you the proton count immediately!
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16.
The molecular lattice of iodine is held together by
1. A.dative bond
2. B.metallic bond
3. C.hydrogen bond
4. D.van der Waal's forces
Show answer
Answer: D. van der Waal's forces
AI explanation
Analysis
The question asks for the type of intermolecular force responsible for holding the molecular lattice of iodine ( $I_2$ ) together.
Concept Explanation
Iodine is a non-metal that exists as a diatomic molecule ( $I_2$ ). In its solid state, iodine forms a molecular crystal lattice. To understand what holds this lattice together, we look at the nature of the molecules:
Non-polar nature: Iodine molecules are non-polar because the two iodine atoms share electrons equally.
Intermolecular forces: Since the molecules are non-polar, they do not experience strong electrostatic attractions like ionic or covalent bonds. Instead, they are held together by weak van der Waals forces (specifically, London dispersion forces). These forces arise from temporary fluctuations in electron distribution, creating temporary dipoles that induce dipoles in neighboring molecules.
Step-by-Step Solution
Identify the structure: Iodine ( $I_2$ ) is a molecular solid.
Evaluate the bonds: • Covalent bonds: These exist within the $I_2$ molecule (holding the two iodine atoms together), but not between the molecules in the lattice. • Metallic bonds: These only occur in metals (e.g., iron, copper), which iodine is not. • Hydrogen bonds: These require a hydrogen atom bonded to a highly electronegative atom (N, O, or F). Iodine does not meet this criteria. • Van der Waals forces: These are the weak attractive forces that exist between neutral, non-polar molecules.
Conclusion: Because the iodine molecules are non-polar and neutral, the only forces strong enough to hold them in a lattice structure at room temperature are van der Waals forces.
Correct Option
The correct option is D.
Exam Tip
Whenever you see questions about the physical properties of non-polar molecular solids (like Iodine, $CO_2$ , or Naphthalene), remember that they generally have low melting points and are held together by van der Waals forces. If the question asks about the bond inside the molecule, it is a covalent bond; if it asks about the force between the molecules in the lattice, it is van der Waals forces.
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17.
with conc H2SO4 as catalyst CH3COOH + C2H5OH → CH3COOC2H5 + H2O
1. A.esterification
2. B.Condensation
3. C.saponification
4. D.neutralization
Show answer
Answer: A. esterification
AI explanation
Analysis of the Question
The reaction provided is: CH₃COOH (Ethanoic acid) + C₂H₅OH (Ethanol) → CH₃COOC₂H₅ (Ethyl ethanoate) + H₂O (Water)
You are asked to identify the specific type of chemical reaction occurring when a carboxylic acid reacts with an alcohol in the presence of a concentrated sulfuric acid catalyst.
Concept Explanation
This reaction is a classic example of esterification.
The Reactants: A carboxylic acid (CH₃COOH) and an alcohol (C₂H₅OH).
The Catalyst: Concentrated sulfuric acid (H₂SO₄) acts as both a catalyst and a dehydrating agent, which helps remove the water molecule formed during the reaction.
The Product: The main product is an ester (CH₃COOC₂H₅), which is characterized by the functional group -COOR. Esters are generally known for their sweet, fruity smells.
Let's look at why the other options are incorrect:
Condensation: While esterification is technically a type of condensation reaction (because a small molecule like water is removed), "esterification" is the more specific and accurate term for the reaction between an acid and an alcohol.
Saponification: This is the exact opposite of esterification; it is the alkaline hydrolysis of an ester to produce soap and glycerol.
Neutralization: This is the reaction between an acid and a base to form salt and water (e.g., HCl + NaOH → NaCl + H₂O).
Step-by-Step Solution
Identify the functional groups: We have a carboxylic acid (-COOH) and an alcohol (-OH).
Observe the reaction type: When these two functional groups combine, the -OH from the acid and the -H from the alcohol combine to form water (H₂O).
Identify the product: The remaining parts join to form an ester linkage (-COO-).
Conclusion: The process of forming an ester from an acid and an alcohol is defined as esterification.
Correct Answer
The correct option is A.
Exam Tip
Whenever you see a reaction involving an organic acid and an alcohol with concentrated H₂SO₄, immediately look for "esterification" in the options. If you are ever asked about the reverse process (breaking an ester down), remember that saponification is the process used to make soap from fats (which are esters).
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18.
The condition required for corrosion to take place is the presence of
1. A.water and carbon (IV) oxide
2. B.water, carbon (IV) oxide and oxygen
3. C.oxygen and carbon (IV) oxide
4. D.water and oxygen
Show answer
Answer: D. water and oxygen
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19.
The function of zinc electrode in a galvanic cells is that it
1. A.undergoes reduction
2. B.serves as the positive electrode
3. C.production of electons
4. D.uses up electrons
Show answer
Answer: C. production of electons
AI explanation
Analysis
This question tests your understanding of the Daniell cell (a common type of galvanic or voltaic cell), specifically the role of the zinc electrode in the redox reaction.
Concept Explanation
In a galvanic cell, chemical energy is converted into electrical energy through a spontaneous redox reaction. The cell consists of two half-cells:
The Anode: This is where oxidation occurs (loss of electrons). In a standard zinc-copper cell, the zinc electrode acts as the anode.
The Cathode: This is where reduction occurs (gain of electrons). In this cell, the copper electrode acts as the cathode.
Because the zinc electrode undergoes oxidation ( $Zn_{(s)} \rightarrow Zn^{2+}_{(aq)} + 2e^-$ ), it releases electrons into the external circuit. Therefore, the zinc electrode is the source of electrons for the circuit.
Step-by-Step Solution
Identify the reaction at the Zinc electrode: Zinc metal ( $Zn$ ) loses two electrons to become zinc ions ( $Zn^{2+}$ ). This process is called oxidation.
Determine the role: Since electrons are being produced by this oxidation process, the zinc electrode acts as the electron donor.
Evaluate the options: • A: Incorrect. Reduction happens at the cathode, not the zinc anode. • B: Incorrect. The anode in a galvanic cell is the negative electrode, not the positive one. • C: Correct. By undergoing oxidation, the zinc electrode releases electrons into the circuit. • D: Incorrect. The cathode uses up electrons; the anode produces them.
Conclusion
The zinc electrode functions as the anode where oxidation takes place, resulting in the release (production) of electrons.
Exam Tip: Remember the mnemonic "AN OX" (Anode = Oxidation) and "RED CAT" (Reduction = Cathode). In galvanic cells, the Anode is always negative, and the Cathode is always positive.
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20.
A suitable solvent for iodine and naphthalene is
1. A.carbon (IV) sulphide
2. B.ethanol
3. C.water
4. D.benzene
Show answer
Answer: D. benzene
AI explanation
Analysis
This question tests your understanding of the principle of "like dissolves like" in chemistry. You are asked to identify a solvent that can dissolve both iodine ( $I_2$ ) and naphthalene ( $C_{10}H_8$ ).
Concept: Solubility and Polarity
Iodine ( $I_2$ ): This is a non-polar covalent molecule.
Naphthalene ( $C_{10}H_8$ ): This is also a non-polar organic compound.
The Principle: In chemistry, polar solvents (like water) dissolve polar solutes and ionic compounds. Non-polar solvents dissolve non-polar solutes. Since both iodine and naphthalene are non-polar, they require a non-polar organic solvent to dissolve.
Step-by-Step Evaluation
Water ( $H_2O$ ): Water is a highly polar solvent. It will not dissolve non-polar substances like iodine or naphthalene.
Ethanol ( $C_2H_5OH$ ): While ethanol has some organic character, it is polar due to the hydroxyl (-OH) group. It is not the most suitable solvent for these specific non-polar solutes compared to non-polar organic solvents.
Carbon (IV) sulphide ( $CS_2$ ): This is a non-polar solvent. It is an excellent solvent for iodine and many organic compounds. However, in the context of standard chemistry curricula (like JAMB), we must compare it with other options provided.
Benzene ( $C_6H_6$ ): Benzene is a classic non-polar organic solvent. It is widely used in laboratories to dissolve non-polar substances like naphthalene and iodine.
In many Nigerian secondary school chemistry textbooks, benzene is the standard example cited for dissolving naphthalene and iodine.
Exam Tip
Remember the phrase "Like dissolves like."
Polar solvents: Water, Ethanol.
Non-polar solvents: Benzene, Carbon (IV) sulphide, Petrol, Kerosene. If you see iodine or naphthalene in a question, immediately look for an organic, non-polar solvent like benzene!
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21.
A chemical reaction which the hydration energy is greater than the lattice energy is referred to as
1. A.a spontaneous reaction
2. B.an endothermic reaction
3. C.an exothermic reaction
4. D.a reversible reaction
Show answer
Answer: C. an exothermic reaction
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22.
An effect of thermal pollution on water bodies is that the
1. A.volume of water reduces
2. B.volume of chemical waste increase
3. C.level of oxides of nitrogen increase
4. D.level of oxygen reduces
Show answer
Answer: D. level of oxygen reduces
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23.
The relative atomic mass of a naturally occurring lithium consisting of 90% $^7 _3$ Li and $^6 _3$ 10% Li is
1. A.6.9
2. B.7.1
3. C.6.2
4. D.6.8
Show answer
Answer: A. 6.9
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24.
The principle of column chromatography is based on the ability of the constituents to
1. A.move at different speeds in the column
2. B.dissolve in each other in the column
3. C.react with the solvent in the column
4. D.react with each other in the column
Show answer
Answer: A. move at different speeds in the column
AI explanation
Analysis of the Question
This question tests your understanding of Separation Techniques in Chemistry, specifically Chromatography. You are asked to identify the fundamental principle that allows column chromatography to separate a mixture into its individual components.
Concept Explanation
Chromatography is a technique used to separate components of a mixture based on the differential distribution of the components between two phases:
Stationary Phase: A solid or liquid material that stays fixed in the column.
Mobile Phase: A solvent that moves through the stationary phase.
As the mobile phase carries the mixture through the column, each component interacts differently with the stationary phase (e.g., through adsorption or partition). Because some components "stick" more to the stationary phase than others, they move through the column at different rates. The component that interacts least with the stationary phase travels the fastest, while the component that interacts most travels the slowest.
Step-by-Step Solution
Consider the process: In column chromatography, you pour a mixture into a column packed with an adsorbent (stationary phase). You then add a solvent (mobile phase) to wash the mixture down.
Evaluate the movement: Because each constituent has a different affinity for the stationary phase, they do not travel at the same velocity.
Analyze the options: • Option A: This is correct because the separation is strictly dependent on the different speeds (or rates of migration) at which the components move through the column. • Option B: Components do not need to dissolve in each other; they are separated from each other. • Option C: While they interact with the solvent, the principle is about the rate of movement, not just the reaction. • Option D: If they reacted with each other, they would form new compounds, which is the opposite of what we want in a separation process.
Conclusion
The separation in column chromatography occurs because the constituents of the mixture have different affinities for the stationary phase, causing them to move through the column at different speeds.
Exam Tip: Whenever you see a question about chromatography (paper, thin-layer, or column), remember the keyword "Differential Migration." If the components moved at the same speed, they would never separate!
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25.
choose the correct answer in the option above. Which of the following is a primary amine?
1. A.A
2. B.B
3. C.C
4. D.D
Show answer
Answer: D. D
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26.
Two organic compounds K and L were treated with a few drops of Fehling's solutions respectively . K formed a brick-red precipitate while L, remains unaffected. The compound K is an
1. A.alkanol
2. B.alkane
3. C.alkanal
4. D.alkanone
Show answer
Answer: C. alkanal
AI explanation
1. Analyze the Question
The question tests your knowledge of functional group identification in organic chemistry using chemical tests. Specifically, it asks you to identify a compound that reacts with Fehling's solution to produce a brick-red precipitate.
2. Explain the Concept
Fehling's solution is a chemical reagent used to distinguish between aldehydes (alkanals) and ketones (alkanones).
Fehling's Test: When Fehling's solution (a mixture of Fehling's A and B) is heated with an alkanal (aldehyde), the aldehyde is oxidized to a carboxylic acid, and the copper(II) ions in the solution are reduced to copper(I) oxide, which forms a brick-red precipitate.
Ketones (Alkanones): Ketones are generally resistant to oxidation and do not react with Fehling's solution. Therefore, the solution remains unchanged (blue).
Alkanols and Alkanes: These do not react with Fehling's solution under standard conditions.
3. Show the Solution
Step 1: Identify the purpose of the test. The formation of a brick-red precipitate is a positive test for the presence of an aldehyde group (-CHO).
Step 2: Match the result to the functional group. Since compound K produced the brick-red precipitate, K must be an alkanal.
Step 3: Evaluate the options. • Alkanol: Does not react with Fehling's solution. • Alkane: Does not react with Fehling's solution. • Alkanal: Reacts with Fehling's solution to give a brick-red precipitate. • Alkanone: Does not react with Fehling's solution.
4. Identify the Answer
Based on the chemical properties of aldehydes, compound K is an alkanal.
Correct Option: C
5. Exam Tip
Remember the "Tollens' and Fehling's Rule": Both Tollens' reagent (silver mirror test) and Fehling's solution are specific to alkanals. If you see "brick-red precipitate" or "silver mirror," immediately think of an alkanal (aldehyde). Ketones are "too stubborn" to react with these mild oxidizing agents!
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27.
Bronze is preferred to copper in the making of medals because it
1. A.is stronger
2. B.can withstand low temperature
3. C.is lighter
4. D.has low tensile strength
Show answer
Answer: A. is stronger
AI explanation
Analysis
The question asks for the reason why bronze is preferred over pure copper for manufacturing medals. To answer this, we must look at the properties of pure metals versus alloys.
Concept Explanation
Copper: Copper is a pure metal. In its pure state, the atoms are arranged in regular layers that can easily slide over one another when force is applied. This makes pure copper relatively soft and malleable.
Bronze: Bronze is an alloy—a mixture of copper and tin. When tin is added to copper, the tin atoms (which are a different size) disrupt the regular arrangement of the copper atoms. This makes it much harder for the layers to slide over each other.
Alloying: The primary purpose of creating alloys like bronze is to improve the mechanical properties of the base metal, specifically increasing its hardness and strength.
Step-by-Step Solution
Compare Properties: Pure copper is soft and easily deformed. Bronze, being an alloy, is significantly harder and more durable.
Evaluate Options: • A (is stronger): Because the atoms in the alloy are locked in place by the different-sized atoms of the alloying element (tin), the material is much stronger and more resistant to deformation than pure copper. This is the primary reason it is used for medals, which need to maintain their shape and detail over time. • B (can withstand low temperature): While true, this is not the primary reason for choosing bronze over copper for medals. • C (is lighter): Bronze is generally denser than copper because tin is a relatively heavy metal; therefore, it is not lighter. • D (has low tensile strength): This is incorrect. Alloys are specifically designed to have higher tensile strength than their constituent pure metals.
Conclusion
Bronze is chosen for medals because the alloying process makes it harder and more durable (stronger) than pure copper, ensuring the medals do not bend or scratch easily.
Exam Tip: Whenever you see a question about alloys (like Brass, Bronze, or Steel), always remember that the main goal of alloying is to increase strength and hardness and to prevent corrosion.
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28.
Which of the following is a deliquescent compound?
1. A.NaNO3
2. B.CaCl2
3. C.CuO
4. D.Na2CO3.10H2O
Show answer
Answer: B. CaCl2
AI explanation
Analysis of the Question
The question asks us to identify a deliquescent compound from the given list. To answer this, we must distinguish between the different ways substances interact with atmospheric water vapor.
Concept Explanation
Deliquescence: This occurs when a substance absorbs so much moisture from the atmosphere that it eventually dissolves in the absorbed water to form a solution. Common examples include Calcium chloride ( $CaCl_2$ ) and Sodium hydroxide ( $NaOH$ ).
Efflorescence: This occurs when a hydrated salt loses its water of crystallization to the atmosphere upon exposure. An example is washing soda ( $Na_2CO_3 \cdot 10H_2O$ ), which loses water to become a white powder.
Hygroscopy: This refers to substances that absorb moisture from the atmosphere but do not necessarily dissolve in it (e.g., concentrated $H_2SO_4$ or silica gel).
Step-by-Step Solution
Analyze Option A ( $NaNO_3$ ): Sodium nitrate is hygroscopic, but it is not typically classified as deliquescent.
Analyze Option B ( $CaCl_2$ ): Calcium chloride is a classic example of a deliquescent substance. It is so effective at absorbing moisture that it is widely used in laboratories as a drying agent (desiccant) in desiccators. It absorbs water until it turns into a liquid solution.
Analyze Option C ( $CuO$ ): Copper(II) oxide is an insoluble metal oxide and does not absorb moisture from the air.
Analyze Option D ( $Na_2CO_3 \cdot 10H_2O$ ): This is a hydrated salt. As mentioned in the concept section, this substance is efflorescent, meaning it loses water to the atmosphere, not the other way around.
Comparing these, $CaCl_2$ is the only substance listed that exhibits deliquescence.
Conclusion
Exam Tip
To remember the difference:
Deliquescent = Dissolves in the water it absorbs.
Efflorescent = Exits (loses) water to the air.
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29.
The functional groups present in the compound above are
1. A.alkene and halo-group
2. B.hydroxyl and chloro-group
3. C.alkene and chloro-group
4. D.hydroxyl and halo-group
Show answer
Answer: C. alkene and chloro-group
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30.
Which of the following is NOT an alkali?
1. A.NH3
2. B.Mg(OH)2
3. C.Ca(OH)2
4. D.NaOH
Show answer
Answer: B. Mg(OH)2
AI explanation
Analysis
The question asks us to identify which of the given substances is not an alkali. To answer this, we must distinguish between a "base" and an "alkali."
Concept Explanation
Base: A base is a substance that reacts with an acid to produce salt and water only. Most metal oxides and hydroxides are bases.
Alkali: An alkali is a soluble base. In other words, all alkalis are bases, but not all bases are alkalis. Alkalis dissolve in water to produce hydroxide ions ( $OH^-$ ).
Let’s evaluate the options based on their solubility in water:
NaOH (Sodium Hydroxide): Highly soluble in water. It is a strong alkali.
Ca(OH)₂ (Calcium Hydroxide): Known as "limewater" when in solution. It is moderately soluble and acts as an alkali.
NH₃ (Ammonia): When dissolved in water, it forms ammonium hydroxide ( $NH_4OH$ ), which is a weak alkali.
Mg(OH)₂ (Magnesium Hydroxide): This is a base, but it is insoluble (or very sparingly soluble) in water. Because it does not dissolve significantly to produce a high concentration of $OH^-$ ions in solution, it is classified as a base but not an alkali.
Step-by-Step Solution
Identify the definition: An alkali must be soluble in water.
Test the options: • NaOH: Soluble $\rightarrow$ Alkali. • Ca(OH)₂: Soluble $\rightarrow$ Alkali. • NH₃: Soluble $\rightarrow$ Alkali. • Mg(OH)₂: Insoluble in water $\rightarrow$ Base, but not an alkali.
Conclusion: Since $Mg(OH)_2$ does not dissolve in water to form an alkaline solution, it is the correct choice.
Exam Tip
Remember the mnemonic: "All alkalis are bases, but not all bases are alkalis." If you see a metal hydroxide that is insoluble (like $Mg(OH)_2$ , $Fe(OH)_3$ , or $Cu(OH)_2$ ), it is a base, but it is definitely not an alkali.
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31.
What is the concentration of a solution containing 2g of NaOH in 100cm3 of solution? [Na = 23, O = 16, H = 1]
1. A.0.40 mol $dm^{-3}$
2. B.0.50 mol $dm^{-3}$
3. C.0.05 mol $dm^{-3}$
4. D.0.30 mol $dm^{-3}$
Show answer
Answer: B. 0.50 mol $dm^{-3}$
AI explanation
Analysis
To find the concentration of the solution, we need to determine how many moles of solute (NaOH) are present in a specific volume of solution (expressed in $dm^3$ ).
Concept
The concentration ( $C$ ) in $mol/dm^3$ is calculated using the formula:
$C = \frac{n}{V}$
Where:
$n$ = number of moles of the solute
$V$ = volume of the solution in $dm^3$
To find the number of moles ( $n$ ), we use:
$n = \frac{\text{mass}}{\text{molar mass}}$
Step-by-Step Solution
Step 1: Calculate the molar mass of NaOH
Na = 23, O = 16, H = 1
Molar mass of NaOH = $23 + 16 + 1 = 40 \, g/mol$
Step 2: Calculate the number of moles ( $n$ ) of NaOH
Mass given = $2 \, g$
$n = \frac{2 \, g}{40 \, g/mol} = 0.05 \, mol$
Step 3: Convert the volume from $cm^3$ to $dm^3$
$1000 \, cm^3 = 1 \, dm^3$
$100 \, cm^3 = \frac{100}{1000} \, dm^3 = 0.1 \, dm^3$
Step 4: Calculate the concentration ( $C$ )
$C = \frac{0.05 \, mol}{0.1 \, dm^3}$
$C = 0.5 \, mol/dm^3$
Conclusion
The calculated concentration is 0.50 mol $dm^{-3}$ . This matches option B.
Exam Tip
Always remember the conversion factor: $1 \, dm^3 = 1000 \, cm^3$ . A common mistake in JAMB Chemistry is forgetting to convert $cm^3$ to $dm^3$ , which leads to an answer that is 1000 times larger than the correct one. Also, ensure you always calculate the molar mass correctly from the atomic masses provided in the bracket!
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32.
In the laboratory preparation of oxygen, dried oxygen is usually collected over
1. A.hydrochloric acid
2. B.mercury
3. C.calcium chloride
4. D.tetraoxosulphate (VI) acid
Show answer
Answer: B. mercury
AI explanation
Analysis of the Question
The question asks for the appropriate method of collecting dried oxygen gas in a laboratory setting. We need to identify which substance or condition allows for the collection of oxygen without reacting with it or being displaced by it in a way that compromises the gas.
Concept Explanation
In the laboratory, oxygen is typically prepared by the thermal decomposition of potassium trioxochlorate(V) ( $KClO_3$ ) using manganese(IV) oxide ( $MnO_2$ ) as a catalyst.
When collecting gases, the method depends on the gas's solubility and density:
Downward displacement of water: Used for gases that are only slightly soluble in water (like oxygen). However, if the gas must be dried, collecting it over water introduces moisture.
Upward displacement of air: Used for gases that are less dense than air.
Collection over mercury: Mercury is a dense liquid metal that does not react with oxygen. Because oxygen is not soluble in mercury and does not react with it, mercury is an ideal medium for collecting gases that might otherwise react with water or other common laboratory liquids.
Step-by-Step Solution
Evaluate Option A (Hydrochloric acid): Oxygen is a gas, and hydrochloric acid is a liquid. Oxygen does not react with it, but it is not a standard medium for gas collection, and the gas would simply bubble through and escape into the atmosphere.
Evaluate Option B (Mercury): Oxygen is chemically inert toward mercury at room temperature. Because mercury is very dense and does not dissolve oxygen, it provides a perfect seal for collecting the gas without introducing water vapor. This is the standard laboratory method for collecting dry oxygen.
Evaluate Option C (Calcium chloride): Calcium chloride ( $CaCl_2$ ) is a drying agent (desiccant), not a medium for collecting gas. You would pass the oxygen through a U-tube containing calcium chloride to dry it, but you cannot collect a gas "over" a solid.
Evaluate Option D (Tetraoxosulphate(VI) acid): Concentrated tetraoxosulphate(VI) acid ( $H_2SO_4$ ) is also a drying agent. Like calcium chloride, it is used to remove moisture from the gas, not as a collection medium.
Conclusion
Since oxygen is collected over a liquid that does not react with it and does not introduce moisture, mercury is the correct choice.
Exam Tip: Always distinguish between drying agents (like $CaCl_2$ and conc. $H_2SO_4$ ) and collection media (like water or mercury). If a question asks how to dry a gas, look for a desiccant; if it asks how to collect a gas, look for a liquid displacement method.
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33.
The arrangement of particles in crystal lattices can be studied using
1. A.X - rays
2. B.γ - rays
3. C.α - rays
4. D.β - rays
Show answer
Answer: A. X - rays
AI explanation
Analysis
The question asks for the specific scientific tool or type of radiation used to determine the internal structure and arrangement of atoms or ions within a crystal lattice.
Concept Explanation
In chemistry and physics, a crystal lattice is a highly ordered, repeating three-dimensional arrangement of particles (atoms, ions, or molecules). Because these particles are packed extremely closely together (at the atomic scale), we need a probe with a wavelength similar to the distance between these particles to "see" them.
X-rays have wavelengths in the range of 0.01 to 10 nanometers, which corresponds perfectly to the spacing between atoms in a crystal. When X-rays strike a crystal, they undergo diffraction. By analyzing the diffraction pattern produced, scientists can calculate the precise positions of the atoms in the lattice. This technique is known as X-ray Crystallography.
Gamma (γ) rays have much shorter wavelengths and higher energy, making them difficult to control for this specific purpose.
Alpha (α) and Beta (β) particles are forms of ionizing radiation consisting of matter (helium nuclei and electrons, respectively) and are not suitable for diffraction studies of crystal structures.
Step-by-Step Solution
Identify the goal: We need to measure the distance between atoms in a solid.
Evaluate the options: • X-rays: Possess the correct wavelength to interact with atomic planes in a crystal lattice. • γ-rays: Too high-energy; they pass through or damage the sample rather than diffracting off the atomic planes. • α-rays and β-rays: These are particles with mass and charge; they are absorbed by the surface of the crystal and cannot penetrate to reveal the internal lattice structure.
Conclusion: X-ray diffraction is the standard laboratory method used to study crystal structures.
Correct Answer
The correct option is A.
Exam Tip
Whenever you see a question about "crystal structure," "atomic spacing," or "diffraction patterns," immediately look for X-rays. Think of X-rays as the "microscope" for atoms!
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34.This question needs a diagram, table or passage that we don't have yet, so it isn't shown.
35.
Which of the following properties is NOT peculiar to matter?
1. A.kinetic energy of particles increase from solid to gas
2. B.Random motion of particles increases from liquid to gas
3. C.Orderliness of particles increases from gas to liquid
4. D.Random motion of particles increases from gas to solid
Show answer
Answer: D. Random motion of particles increases from gas to solid
AI explanation
Analysis of the Question
The question asks us to identify which of the given statements is NOT a correct description of the properties of matter (specifically regarding the kinetic theory of matter and the states of matter: solid, liquid, and gas).
Explanation of the Concept
According to the Kinetic Theory of Matter:
Kinetic Energy: Particles in a gas have the highest kinetic energy, while particles in a solid have the lowest (they only vibrate about fixed positions). Therefore, kinetic energy increases as you move from solid to liquid to gas.
Random Motion: Gases have particles that move randomly at high speeds. Liquids have more restricted motion, and solids have virtually no translational motion. Thus, random motion increases from solid to liquid to gas.
Orderliness: Solids are highly ordered (lattice structure), liquids have less order, and gases have no order (disordered). Therefore, orderliness increases from gas to liquid to solid.
Step-by-Step Evaluation
Option A: "Kinetic energy of particles increase from solid to gas." This is true. As heat is added, particles gain energy and move faster.
Option B: "Random motion of particles increases from liquid to gas." This is true. Gas particles are free to move in all directions, unlike liquid particles which are held by intermolecular forces.
Option C: "Orderliness of particles increases from gas to liquid." This is true. As you cool a gas into a liquid, the particles become more packed and organized.
Option D: "Random motion of particles increases from gas to solid." This is false. Moving from gas to solid actually decreases random motion because the particles are becoming more fixed and structured.
Conclusion
Since the question asks for the property that is NOT peculiar (or correct) to matter, Option D is the incorrect statement.
Exam Tip: Always remember the "Energy-Motion-Order" rule:
Energy and Motion: Solid < Liquid < Gas
Orderliness: Gas < Liquid < Solid If you ever get confused, think of a crowded bus (solid/liquid) versus a playground (gas).
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36.
The impurities formed during the laboratory preparation of chlorine gas are removed by
1. A.H2O
2. B.NH3
3. C.H2SO4
4. D.HCl
Show answer
Answer: A. H2O
AI explanation
Analysis
In the laboratory preparation of chlorine gas ( $Cl_2$ ), concentrated hydrochloric acid ( $HCl$ ) is reacted with an oxidizing agent like manganese(IV) oxide ( $MnO_2$ ). The resulting gas is typically contaminated with hydrogen chloride gas ( $HCl$ ) and water vapor ( $H_2O$ ). To obtain pure, dry chlorine gas, these impurities must be removed.
Concept
To purify a gas, we use "scrubbing" agents:
Removal of $HCl$ gas: The gas is passed through water ( $H_2O$ ). Since $HCl$ is extremely soluble in water, it dissolves, leaving the chlorine gas behind.
Removal of water vapor: The gas is then passed through concentrated tetraoxosulphate(VI) acid ( $H_2SO_4$ ). Concentrated $H_2SO_4$ is a powerful dehydrating agent that absorbs the remaining moisture.
Step-by-Step Solution
Identify the impurities: The gas produced ( $Cl_2$ ) is mixed with $HCl$ (from the acid used) and water vapor (from the reaction).
First purification stage: The mixture is bubbled through a wash bottle containing water. This removes the $HCl$ gas because $HCl$ is highly soluble in water, whereas $Cl_2$ is only sparingly soluble.
Second purification stage: The gas is then passed through a drying tower containing concentrated $H_2SO_4$ . This removes the water vapor.
Evaluating the options: The question asks for the substance used to remove the impurities (specifically referring to the initial wash). Water is the primary agent used to wash away the $HCl$ impurity.
Conclusion
While $H_2SO_4$ is used to dry the gas, water is the specific reagent used to remove the $HCl$ impurity formed during the preparation.
Exam Tip
Remember the "Wash and Dry" sequence for chlorine: Water to wash away $HCl$ , then Conc. $H_2SO_4$ to dry it. If the question asks what is used to dry the gas, choose $H_2SO_4$ . If it asks what is used to remove impurities (referring to the acid fumes), choose $H_2O$ .
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37.
The importance of sodium aluminate (III) in the treatment of water is to
1. A.cause coagulation
2. B.neutralize acidity
3. C.prevent goitre and tooth decay
4. D.kill germs
Show answer
Answer: A. cause coagulation
AI explanation
Analysis
The question asks for the specific role of sodium aluminate (III), also known as sodium aluminate ( $NaAlO_2$ ), when it is added to water during the treatment process.
Concept Explanation
In water treatment, the process of coagulation is used to remove suspended impurities (like dirt, clay, and organic matter) that are too small to be removed by simple filtration.
Coagulants are chemicals that neutralize the negative charges on these suspended particles, allowing them to clump together into larger particles called flocs. Once these particles become heavy enough, they settle at the bottom of the tank (sedimentation) or can be easily filtered out. Sodium aluminate is a common chemical used for this purpose, especially in water that is slightly acidic or when a rapid coagulation process is required.
Step-by-Step Solution
Identify the chemical: Sodium aluminate ( $NaAlO_2$ ) is an alkaline salt.
Understand the reaction: When added to water, it reacts to form aluminum hydroxide, $Al(OH)_3$ , which is a gelatinous (jelly-like) precipitate.
Mechanism: This gelatinous precipitate acts as a "sticky" agent. It traps suspended particles and impurities, causing them to aggregate (coagulate) into larger masses.
Evaluate the options: • A (Cause coagulation): This aligns with the chemical action of sodium aluminate described above. • B (Neutralize acidity): While sodium aluminate is alkaline, its primary industrial purpose in water treatment is coagulation, not just pH adjustment. • C (Prevent goitre and tooth decay): This is the role of iodine and fluoride additives, respectively, not sodium aluminate. • D (Kill germs): This is the role of disinfectants like chlorine or ozone.
Conclusion
Sodium aluminate is primarily used as a coagulant to clear suspended matter from water. Therefore, the correct option is A.
Exam Tip: Whenever you see questions about water treatment, remember the "Big Three" roles:
Coagulants (like Alum or Sodium Aluminate) for removing suspended particles.
Disinfectants (like Chlorine) for killing germs/bacteria.
Fluoridation (adding Fluoride) for preventing tooth decay.
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38.
How many cations will be produced from a solution of potassium aluminium tetraoxosulphate (VI)?
1. A.3
2. B.4
3. C.1
4. D.2
Show answer
Answer: D. 2
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39.
MnO-4(aq) + Y + 5Fe2+(aq) → Mn2+(aq) + 5Fe2+(aq) + 4H2O(l) In the equation above, Y is
1. A.5H+(aq)
2. B.4H+(aq)
3. C.10H+(aq)
4. D.8H+(aq)
Show answer
Answer: D. 8H+(aq)
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40.
The number of isomers that can be obtained from C $_4$ H $_{10}$ is
1. A.3
2. B.4
3. C.1
4. D.2
Show answer
Answer: D. 2
AI explanation
Analysis
The question asks for the number of structural isomers for the alkane with the molecular formula C $_4$ H $_{10}$ (butane). Isomers are compounds that have the same molecular formula but different structural arrangements of atoms.
Concept
For alkanes, isomers are formed by changing the carbon skeleton (chain isomerism). We start with the straight-chain structure and then try to create branched structures by moving carbon atoms to different positions.
Step-by-Step Solution
Identify the straight-chain isomer: The first structure is the continuous chain of four carbon atoms. This is called n-butane. Structure: $CH_3 - CH_2 - CH_2 - CH_3$
Attempt to create a branched isomer: To create a branch, we take one carbon atom from the main chain and attach it to an internal carbon atom. If we take one carbon from the end of the 4-carbon chain, we are left with a 3-carbon chain (propane) as the parent chain. We then attach the remaining carbon to the middle carbon of the propane chain. This is called 2-methylpropane (or isobutane). Structure: $CH_3 - CH(CH_3) - CH_3$
Check for further isomers: If we try to move the methyl group to the end carbon of the 3-carbon chain, we simply recreate the straight-chain n-butane. Therefore, no other unique structural isomers exist for C $_4$ H $_{10}$ .
Summary of isomers:
n-butane
2-methylpropane
Total number of isomers = 2.
Conclusion
Comparing our result with the options provided, we can see that there are exactly 2 isomers.
Exam Tip
For alkanes, you can use a quick mental check:
C $_1$ to C $_3$ : Only 1 isomer each.
C $_4$ : 2 isomers.
C $_5$ : 3 isomers.
C $_6$ : 5 isomers. Remembering this sequence (1, 1, 1, 2, 3, 5) can save you valuable time during your JAMB exam!
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41.
What type of bond exits between an element X with atomic number 12 and Y with atomic number 17?
1. A.Electrovalent
2. B.Metallic
3. C.Covalent
4. D.Dative
Show answer
Answer: A. Electrovalent
AI explanation
1. Analyze the question
We need to determine the type of chemical bond formed between element X (atomic number 12) and element Y (atomic number 17).
2. Explain the concept
Electronic Configuration: To determine the bonding, we first write the electronic configuration of each element to see how many electrons are in their outermost shells (valence electrons).
Metals vs. Non-metals: • Elements with 1, 2, or 3 valence electrons are typically metals (they lose electrons to become cations). • Elements with 5, 6, or 7 valence electrons are typically non-metals (they gain electrons to become anions).
Bond Types: • Electrovalent (Ionic) bond: Formed by the complete transfer of electrons from a metal to a non-metal. • Covalent bond: Formed by the sharing of electrons between two non-metals.
3. Show the solution
Element X (Atomic number 12): • Electronic configuration: $1s^2 2s^2 2p^6 3s^2$ (or 2, 8, 2). • X has 2 valence electrons. It is a metal (Magnesium). It will lose these 2 electrons to achieve a stable octet structure, forming an $X^{2+}$ ion.
Element Y (Atomic number 17): • Electronic configuration: $1s^2 2s^2 2p^6 3s^2 3p^5$ (or 2, 8, 7). • Y has 7 valence electrons. It is a non-metal (Chlorine). It needs 1 electron to complete its octet, forming a $Y^-$ ion.
The Reaction: Since X is a metal and Y is a non-metal, X will transfer its electrons to Y. Specifically, one atom of X will donate its 2 electrons to two atoms of Y ( $XY_2$ ). This complete transfer of electrons results in an electrovalent (ionic) bond.
4. Identify the answer
The correct option is A.
5. Exam Tip
A simple way to remember this for JAMB: If you see a metal (Group I or II) reacting with a non-metal (Group VI or VII), the bond is almost always Electrovalent/Ionic. If you see two non-metals reacting, it is usually Covalent.
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42.
A few drops of concentrated HNO $_3$ is added to an unknown solution and boiled for a while. If this produces a brown solution, the cation present is likely to be
1. A.Pb2+
2. B.Cu2+
3. C.Fe3+
4. D.Fe2+
Show answer
Answer: D. Fe2+
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43.
At 25o and zymase as catalyst, C6H126 → 2C2H5OH + 2CO2 + energy The reaction above represented by the equation above is useful in the production of
1. A.propanol
2. B.butanol
3. C.methanol
4. D.ethanol
Show answer
Answer: D. ethanol
AI explanation
Analysis of the Question
The question asks you to identify the product of the fermentation process represented by the chemical equation: $C_6H_{12}O_6 \xrightarrow{\text{zymase}} 2C_2H_5OH + 2CO_2 + \text{energy}$
Concept Explanation
This reaction is known as alcoholic fermentation. It is a biological process where yeast (which contains the enzyme zymase) breaks down glucose ( $C_6H_{12}O_6$ ) in the absence of oxygen (anaerobic conditions) to produce alcohol and carbon dioxide.
Glucose ( $C_6H_{12}O_6$ ): The sugar substrate.
Zymase: The biological catalyst (enzyme) found in yeast.
$C_2H_5OH$ : This is the chemical formula for ethanol (ethyl alcohol).
Step-by-Step Solution
Examine the products: The equation explicitly shows the formation of $2C_2H_5OH$ .
Identify the chemical name: • $CH_3OH$ is Methanol. • $C_2H_5OH$ is Ethanol. • $C_3H_7OH$ is Propanol. • $C_4H_9OH$ is Butanol.
Match with options: Since the product is $C_2H_5OH$ , it corresponds directly to ethanol.
Conclusion
The reaction is the standard industrial and laboratory method for producing ethanol from glucose. Therefore, the correct option is D.
Exam Tip
When you see the word "zymase" or "yeast" in a Chemistry question, immediately associate it with the production of ethanol. Also, remember that this reaction is the basis for the production of alcoholic beverages and industrial ethanol.
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44.
An organic compound has an empirical formula CH2O and vapour density of 45. What is the molecular formula? [C = 12, H = 1, O = 16]
1. A.C3H7OH
2. B.C2H5OH
3. C.C3H6O3
4. D.C2H4O2
Show answer
Answer: C. C3H6O3
AI explanation
Analysis
To find the molecular formula of an organic compound, we need to determine the relationship between its empirical formula and its molecular mass. We are given the empirical formula ( $CH_2O$ ) and the vapour density of the compound.
Concept
Molecular Mass: The molecular mass of a substance is twice its vapour density. $ $\text{Molecular Mass} = 2 \times \text{Vapour Density}$ $
Relationship: The molecular formula is a multiple of the empirical formula. $ $\text{Molecular Formula} = (\text{Empirical Formula})_n$ $Where$ n = \frac{\text{Molecular Mass}}{\text{Empirical Formula Mass}}$
Step-by-Step Solution
Step 1: Calculate the molecular mass. Given the vapour density is 45:
$\text{Molecular Mass} = 2 \times 45 = 90$
Step 2: Calculate the empirical formula mass. Using the atomic masses provided ( $C=12, H=1, O=16$ ):
$\text{Empirical Formula Mass} = (1 \times 12) + (2 \times 1) + (1 \times 16)$
$\text{Empirical Formula Mass} = 12 + 2 + 16 = 30$
Step 3: Determine the value of $n$ .
$n = \frac{\text{Molecular Mass}}{\text{Empirical Formula Mass}}$
$n = \frac{90}{30} = 3$
Step 4: Determine the molecular formula. Multiply the empirical formula ( $CH_2O$ ) by $n=3$ :
$\text{Molecular Formula} = (CH_2O) \times 3$
$\text{Molecular Formula} = C_3H_6O_3$
Conclusion
Comparing our result to the given options, $C_3H_6O_3$ corresponds to option C.
Exam Tip
Always remember that Vapour Density is a shortcut to finding the molar mass of a gas or volatile liquid. If you ever forget the formula, just remember that the molecular mass of Hydrogen gas ( $H_2$ ) is 2, and its vapour density is 1; this ratio ( $2:1$ ) applies to all gases!
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45.
Which of the following questions is correct about the periodic table?
1. A.The non-metallic properties of the elements tend to decrease across each period
2. B.The valence electrons of the elements increase progressively across the period
3. C.Elements in the same group have the same numbeer of electron shells
4. D.Elements in the same period have the number of valence electrons
Show answer
Answer: B. The valence electrons of the elements increase progressively across the period
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46.
The property of concentrated H2SO4 that makes it suitable for preparing HNO3 is its
1. A.boiling point
2. B.density
3. C.oxidizing properties
4. D.dehydrating properties
Show answer
Answer: A. boiling point
AI explanation
Analysis
The question asks for the specific chemical or physical property of concentrated tetraoxosulphate(VI) acid ( $H_2SO_4$ ) that allows it to be used in the laboratory preparation of trioxonitrate(V) acid ( $HNO_3$ ).
Concept Explanation
In the laboratory, $HNO_3$ is prepared by heating a mixture of a nitrate salt (like $NaNO_3$ or $KNO_3$ ) with concentrated $H_2SO_4$ . The reaction is: $NaNO_3(s) + H_2SO_4(conc) \rightarrow NaHSO_4(s) + HNO_3(g)$
The key to this preparation is that $HNO_3$ is a volatile acid (it has a low boiling point), while $H_2SO_4$ is a non-volatile acid (it has a very high boiling point). Because $H_2SO_4$ has a much higher boiling point, it remains in the reaction vessel while the $HNO_3$ is driven off as a gas and subsequently condensed. If $H_2SO_4$ were volatile, it would vaporize along with the $HNO_3$ , contaminating the product.
Step-by-Step Solution
Identify the reactants: We are reacting a salt with an acid to produce another acid.
Compare the acids: $HNO_3$ is volatile (boils at approximately 83°C), whereas $H_2SO_4$ is non-volatile (boils at approximately 338°C).
Determine the mechanism: The reaction relies on the fact that the non-volatile acid ( $H_2SO_4$ ) can displace the more volatile acid ( $HNO_3$ ) from its salt.
Evaluate the options: • A. Boiling point: This is the correct property. The high boiling point of $H_2SO_4$ ensures it stays liquid while $HNO_3$ turns to gas. • B. Density: While $H_2SO_4$ is dense, its density is not the reason it displaces $HNO_3$ . • C. Oxidizing properties: $H_2SO_4$ is an oxidizing agent, but this property is not relevant to the displacement of $HNO_3$ . • D. Dehydrating properties: $H_2SO_4$ is a powerful dehydrating agent (it removes water), but this is not the principle behind the preparation of $HNO_3$ .
Conclusion
Exam Tip: Whenever you see a question about the preparation of volatile acids (like $HCl$ or $HNO_3$ ) using $H_2SO_4$ , always look for "non-volatile" or "high boiling point" as the reason. It is a classic JAMB chemistry principle!
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47.This question needs a diagram, table or passage that we don't have yet, so it isn't shown.

2011 JAMB Chemistry Past Questions

Questions

Analysis

Concept Explanation

Step-by-Step Solution

Conclusion

Exam Tip

Analysis

Concept Explanation

Step-by-Step Solution

Exam Tip

Analysis

Concept Explanation

Step-by-Step Breakdown

Final Answer

1. Analyze the Question

2. Explain the Concept

3. Show the Solution

4. Identify the Answer

5. Exam Tip

Analysis of the Question

Concept Explanation

Step-by-Step Solution

Evaluating the Options

Exam Tip

Analysis

Concept

Solution

Conclusion

Analysis of the Question

Concept Explanation

Step-by-Step Solution

Identification of the Answer

Exam Tip

1. Analyze the question

2. Explain the concept

3. Show the solution

4. Identify the answer

5. Tip for your exam

Analysis

Concept Explanation

Step-by-Step Solution

Conclusion

Exam Tip

Analysis

Concept Explanation

Step-by-Step Solution

Conclusion

Exam Tip

Analysis

Concept Explanation

Step-by-Step Solution

Correct Option

Exam Tip

Analysis of the Question

Concept Explanation

Step-by-Step Solution

Correct Answer

Exam Tip

Analysis

Concept Explanation

Step-by-Step Solution

Conclusion

Analysis

Concept: Solubility and Polarity

Step-by-Step Evaluation

Exam Tip

Analysis of the Question

Concept Explanation

Step-by-Step Solution

Conclusion

1. Analyze the Question

2. Explain the Concept

3. Show the Solution

4. Identify the Answer

5. Exam Tip

Analysis

Concept Explanation

Step-by-Step Solution

Conclusion