JAMB UTME - Chemistry - 2011

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Question 2 Report

The property of concentrated H2SO4 that makes it suitable for preparing HNO3 is its

boiling point

density

oxidizing properties Correct answer

dehydrating properties

Answer Details

Read lesson note on Acids, Bases And Salts (JAMB)

Acids, Bases And Salts

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Question 3 Report

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

is stronger Correct answer

can withstand low temperature

is lighter

has low tensile strength

Answer Details

Bronze is preferred to copper in the making of medals because it is stronger. Bronze is an alloy made up of copper and tin, which increases its strength compared to pure copper. This increased strength allows for more intricate designs to be made on the medal without the risk of the medal breaking or becoming distorted. Additionally, bronze has a distinct color that is often associated with medals, making it a popular choice for commemorative or decorative items. The other options mentioned in the question, such as low-temperature resistance or lightness, are not relevant factors in the preference for bronze over copper in medal-making.

Read lesson note on Metals And Their Compounds (JAMB)

Metals And Their Compounds

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Question 4 Report

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

undergoes reduction

serves as the positive electrode

production electons Correct answer

uses up electrons

Answer Details

Read lesson note on Oxidation And Reduction (JAMB)

Read lesson note on Redox Reactions (WAEC)

Oxidation And Reduction

Redox Reactions

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Question 5 Report

The ability of carbon to form long chains is referred to as

alkylation

acylation

catenation Correct answer

carbonation

Answer Details

The ability of carbon to form long chains is referred to as catenation. Catenation is the property of an element to form a long chain or branch of atoms by bonding covalently with other atoms of the same element. Carbon is known for its strong catenation property due to its tetravalency (ability to form four covalent bonds) and small atomic size. This property of carbon allows it to form a variety of organic compounds, including hydrocarbons and polymers, which are the building blocks of life. Therefore, the correct answer is "catenation."

Read lesson note on Chemistry Of Carbon Compounds (Ghana Only) (WAEC)

Read lesson note on Chemistry Of Carbon Compounds (Nigeria Only) (WAEC)

Read lesson note on Chemistry, Industry And The Environment (WAEC)

Chemistry Of Carbon Compounds (Ghana Only)

Chemistry, Industry And The Environment

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Question 6 Report

A chemical reaction which the hydration energy is greater than the lattice energy is referred to as

a spontaneous reaction

an endothermic reaction

an exothermic reaction Correct answer

a reversible reaction

Answer Details

A chemical reaction in which the hydration energy is greater than the lattice energy is referred to as an exothermic reaction. This means that the energy released during the formation of new chemical bonds is greater than the energy required to break the existing bonds. The excess energy is released into the surroundings in the form of heat, causing the reaction to feel warm. This type of reaction typically occurs spontaneously and does not require external energy input to proceed. An example of an exothermic reaction is the combustion of fuels such as gasoline or natural gas, which release heat and energy as they react with oxygen.

Read lesson note on Kinetic Theory Of Matter And Gas Laws (JAMB)

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Question 7 Report

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]

M = E/Q

M = EQ Correct answer

M = Q/E

M = E/2Q

Answer Details

Read lesson note on Electrolysis (JAMB)

Electrolysis

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Question 8 Report

The number of isomers that can be obtained from 04R0 is

Correct answer

Answer Details

Read lesson note on Chemistry Of Carbon Compounds (Nigeria Only) (WAEC)

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Question 9 Report

The molecular lattice of iodine is held together by

dative bond

metallic bond

hydrogen bond

van der Waal's forces Correct answer

Answer Details

The molecular lattice of iodine is held together by van der Waal's forces. Iodine is a diatomic molecule made up of two iodine atoms. The atoms are held together by a covalent bond formed by sharing electrons between them. In the solid state, the iodine molecules are arranged in a lattice structure held together by weak intermolecular forces called van der Waal's forces. These forces arise due to temporary fluctuations in the electron density around the atoms, which induce dipole moments in neighboring molecules. The dipole moments attract each other, creating a weak force that holds the molecules together in the lattice structure. Therefore, out of the options given, van der Waal's forces are responsible for holding the molecular lattice of iodine together.

Read lesson note on Atomic Structure And Bonding (JAMB)

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Question 10 Report

What is the concentration of a solution containing 2g of NaOH in 100cm3 of solution?
[Na = 23, O = 16, H = 1]

0.40 mol dm-3

0.50 mol dm-3 Correct answer

0.05 mol dm-3

0.30 mol dm-3

Answer Details

To find the concentration of a solution, we need to calculate the number of moles of solute (NaOH) in 100 cm³ of solution. First, we need to find the molar mass of NaOH: Na = 23 g/mol, O = 16 g/mol, H = 1 g/mol, so the molar mass of NaOH is 23 + 16 + 1 = 40 g/mol. We are given that there are 2 g of NaOH in the solution, so the number of moles of NaOH is: 2 g ÷ 40 g/mol = 0.05 mol Now we can calculate the concentration: Concentration = Number of moles ÷ Volume of solution Concentration = 0.05 mol ÷ 0.1 dm³ = 0.5 mol/dm³ So the concentration of the solution is 0.50 mol/dm³. Therefore, the correct option is: - 0.50 mol dm⁻³

Read lesson note on Kinetic Theory Of Matter And Gas Laws (JAMB)

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Question 11 Report

The arrangement of particles in crystal lattices can be studied using

X - rays Correct answer

γ - rays

α - rays

β - rays

Answer Details

The arrangement of particles in crystal lattices can be studied using X-rays. X-rays have a very short wavelength, which allows them to diffract when they pass through a crystal lattice. The diffraction pattern created by the X-rays provides information about the spacing and arrangement of the atoms in the crystal. By analyzing the diffraction pattern, scientists can determine the crystal structure and the positions of the atoms within the lattice. Gamma rays, alpha rays, and beta rays are not typically used to study crystal structures, as they have different properties and are not well-suited for this purpose.

Read lesson note on Atomic Structure And Bonding (JAMB)

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Question 12 Report

Which of the following compounds will undergo polymerization reaction?

C2H4 Correct answer

C2H5COOH

C2H6

C2H5OH

Answer Details

Polymerization is a chemical reaction that involves the combination of many small molecules to form a large molecule with repeating structural units, called a polymer. In order for a compound to undergo polymerization, it should have a monomer or multiple monomers that can form a repeating pattern. Looking at the options given, compound (C2H4)n, also known as polyethylene, is a polymer and can undergo polymerization reaction. This is because its monomer, ethylene, contains a double bond that can break and form a chain of repeating units. On the other hand, compounds (C2H5COOH), (C2H6), and (C2H5OH) are not likely to undergo polymerization reaction because they do not have functional groups that can easily form repeating units. Therefore, the compound that will undergo polymerization reaction is (C2H4)n.

Read lesson note on Chemistry Of Carbon Compounds (Nigeria Only) (WAEC)

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Question 13 Report

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

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

The valence electrons of the elements increase progressively across the period Correct answer

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

Elements in the same period have the number of valence electrons

Answer Details

Read lesson note on Atomic Structure And Bonding (JAMB)

Read lesson note on Periodic Chemistry (Ghana Only) (WAEC)

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Question 14 Report

Which of the following noble gases is commonly found in the atmosphere?

Xenon

Neon

Helium

Argon Correct answer

Answer Details

Among the options listed, the noble gas commonly found in the atmosphere is Argon. Argon makes up approximately 0.9% of the Earth's atmosphere and is the third most abundant gas after nitrogen and oxygen. Neon and helium are also noble gases, but they are not commonly found in the atmosphere because they are both lighter than air and tend to escape to the upper atmosphere. Xenon, on the other hand, is a rare gas and only exists in trace amounts in the atmosphere.

Read lesson note on Periodic Chemistry (Nigeria Only) (WAEC)

Periodic Chemistry (Nigeria Only)

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Question 15 Report

N2O4(g) ↔ 2NO2(g) ΔH = +ve

In the reaction above, an increase in temperature will

increase the value of the equilibrium constant Correct answer

decreases the value of the equilibrium constant

increase in the reactant production

shift the equilibrium to the left

Answer Details

The given chemical equation shows a reversible reaction where nitrogen dioxide (NO2) and dinitrogen oxide (N2O4) are in equilibrium. The reaction is endothermic, which means it absorbs heat. According to Le Chatelier's principle, an increase in temperature will favor the endothermic reaction, which absorbs heat. As a result, the equilibrium will shift in the direction that consumes heat, which in this case is the forward reaction. Therefore, an increase in temperature will shift the equilibrium to the right, favoring the formation of more NO2 gas and reducing the concentration of N2O4. As a result, the equilibrium constant (K) for this reaction, which is the ratio of products to reactants at equilibrium, will increase. Thus, the correct answer is "increase the value of the equilibrium constant."

Read lesson note on Chemical Kinetics And Equilibrium System (Nigeria Only) (WAEC)

Read lesson note on Chemical Kinetics And Equilibrium Systems (Ghana Only) (WAEC)

Chemical Kinetics And Equilibrium System (Nigeria Only)

Chemical Kinetics And Equilibrium Systems (Ghana Only)

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Question 16 Report

At 25o and zymase as catalyst,

C6H126 → 2C2H5OH + 2CO2 + energy

The reaction above represented by the equation above is useful in the production of

propanol

butanol

methanol

ethanol Correct answer

Answer Details

The given equation represents the process of fermentation, in which glucose (C6H12O6) is converted into ethanol (C2H5OH) and carbon dioxide (CO2), with the help of the enzyme zymase. Therefore, the correct answer is ethanol.

Read lesson note on Kinetic Theory Of Matter And Gas Laws (JAMB)

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Question 17 Report

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

cause coagulation Correct answer

neutralize acidity

prevent goitre and tooth decay

kill germs

Answer Details

Sodium aluminate (III) is important in water treatment because it causes coagulation. Coagulation is the process of removing suspended particles from water by causing them to stick together and form larger particles that can be easily removed. Sodium aluminate (III) is added to water to create positively charged particles, which attract and bind with negatively charged particles in the water. This causes the suspended particles to clump together and settle at the bottom, making it easier to remove them from the water. Therefore, sodium aluminate (III) helps to improve the quality of water by making it cleaner and safer to use.

Read lesson note on Solubility Of Substances (Ghana Only) (WAEC)

Solubility Of Substances (Ghana Only)

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Question 18 Report

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

alkanol

alkane

alkanal Correct answer

alkanone

Answer Details

Fehling's solution is a chemical test used to distinguish between reducing sugars (which have a free aldehyde or ketone group) and non-reducing sugars (which do not have a free aldehyde or ketone group). When a reducing sugar is added to Fehling's solution and heated, it reduces the copper(II) ions in the solution to form a brick-red precipitate of copper(I) oxide. In this case, compound K formed a brick-red precipitate when treated with Fehling's solution, indicating that it is a reducing sugar or a compound that contains a free aldehyde or ketone group. On the other hand, compound L remained unaffected, indicating that it is not a reducing sugar and does not contain a free aldehyde or ketone group. Among the given options, the only compound that contains a free aldehyde or ketone group is an alkanal. Therefore, the compound K is an alkanal.

Read lesson note on Organic Compounds (JAMB)

Organic Compounds

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Question 19 Report

An organic compound has an empirical formula CH2O and vapour density of 45.

What is the molecular formula?

[C = 12, H = 1, O = 16]

C3H7OH

C2H5OH

C3H6O3 Correct answer

C2H4O2

Answer Details

Read lesson note on Structure Of The Atom (Ghana Only) (WAEC)

Read lesson note on Chemistry Of Carbon Compounds (Nigeria Only) (WAEC)

Structure Of The Atom (Ghana Only)

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Question 20 Report

Which of the following is NOT an alkali?

NH3 Correct answer

Mg(OH)2

Ca(OH)2

NaOH

Answer Details

The question is asking to identify the option that is NOT an alkali. An alkali is a base that dissolves in water to form a solution with a pH greater than 7. Therefore, we need to identify the option that is not a base or does not dissolve in water to form a solution with a pH greater than 7. Among the options provided, the only option that is NOT an alkali is NH3. NH3 is ammonia, which is a gas at room temperature and does not dissolve in water to form a solution with a pH greater than 7. Therefore, the correct answer is NH3.

Read lesson note on Acids, Bases And Salts (Ghana Only) (WAEC)

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Question 21 Report

With conc H2SO4 as catalyst

CH3COOH + C2H5OH → CH3COOC2H5 + H2O

esterification Correct answer

Condensation

saponification

neutralization

Answer Details

The given chemical reaction involves the formation of an ester from a carboxylic acid (CH3COOH) and an alcohol (C2H5OH) in the presence of a catalyst (H2SO4). This process is known as esterification. Therefore, the correct option is: Esterification.

Read lesson note on Acids, Bases And Salts (JAMB)

Read lesson note on Organic Compounds (JAMB)

Acids, Bases And Salts

Organic Compounds

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Question 22 Report

The diagram above best illustrates the effect of decrease in

concentration Correct answer

temperature

surface area

pressure

Answer Details

The diagram shows a decrease in the rate of reaction over time. The most likely explanation for this effect is a decrease in the concentration of the reactants. This is because a lower concentration means that there are fewer reactant molecules available to collide and react with each other, resulting in a slower rate of reaction. Decreases in temperature, surface area, or pressure can also affect the rate of reaction, but these factors are not as clearly illustrated by the diagram. A decrease in temperature would cause the reaction to slow down, but the effect would be gradual rather than sudden. A decrease in surface area would also slow down the reaction, but it would not necessarily cause a sudden drop in the rate of reaction. A decrease in pressure might speed up the reaction if the reactants are in the gas phase, but again, the effect would not be as clearly illustrated by the diagram.

Read lesson note on Kinetic Theory Of Matter And Gas Laws (JAMB)

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Question 23 Report

From the diagram above, find the amount of solute deposited when 200 cm3 of the solution is cooled from 55oC to 40oC

0.10 mole

0.20mole Correct answer

0.01 mole

0.02 mole

Answer Details

Read lesson note on SOLUBILITY OF SUBSTANCES (Nigeria Only) (WAEC)

SOLUBILITY OF SUBSTANCES (Nigeria Only)

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Question 24 Report

CH4(g) + Cl2(g) → CH3 Cl(s) + HCl(g)

The major factor that influence the rate of the reaction above is

catalyst

temperature

concentration

light Correct answer

Answer Details

Read lesson note on Rates Of Chemical Reaction (JAMB)

Rates Of Chemical Reaction

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Question 25 Report

The impurities formed during the laboratory preparation of chlorine gas are removed by

H2O Correct answer

NH3

H2SO4

HCl

Answer Details

The laboratory preparation of chlorine gas often produces impurities which need to be removed before the gas can be used. The question asks which substance is used to remove these impurities. The correct answer is not explicitly stated in the question, but can be determined through knowledge of chemistry. Chlorine gas is often prepared by reacting hydrochloric acid (HCl) with manganese dioxide (MnO2). However, impurities such as excess hydrochloric acid, water, and other gases may be present in the resulting gas mixture. To remove these impurities, a substance that can react with them must be used. Hydrogen peroxide (H2O2) or sodium hydroxide (NaOH) may be used to remove excess hydrochloric acid. Calcium carbonate (CaCO3) or sodium carbonate (Na2CO3) may be used to remove acidic gases such as carbon dioxide (CO2) and sulfur dioxide (SO2). Water may be removed by passing the gas through a drying agent such as concentrated sulfuric acid (H2SO4) or calcium chloride (CaCl2). Based on the given options, the most appropriate answer is "H2O".

Read lesson note on Acids, Bases And Salts (JAMB)

Acids, Bases And Salts

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Question 26 Report

MnO-4(aq) + Y + 5Fe2+(aq) ? Mn2+(aq) + 5Fe2+(aq) + 4H2O(l)

In the equation above, Y is

5H+(aq)

4H+(aq)

10H+(aq)

8H+(aq) Correct answer

Answer Details

Read lesson note on Kinetic Theory Of Matter And Gas Laws (JAMB)

Read lesson note on Redox Reactions (WAEC)

Read lesson note on Energy Changes (JAMB)

Redox Reactions

Energy Changes

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Question 27 Report

CH3COOH(aq) + OH-(aq) ↔ CH3COO-(aq) + H2O(l)

In the reaction above ,CH3COO-(aq) is

conjugate base Correct answer

acid

base

conjugate acid

Answer Details

In the given chemical reaction, CH3COOH reacts with OH- to form CH3COO- and H2O. The compound CH3COOH is an acid because it donates a proton (H+) to the OH- ion, which accepts the proton to form H2O. As a result, CH3COO- is formed, which is the conjugate base of CH3COOH. So, the answer is "conjugate base."

Read lesson note on Chemical Bonds (Ghana Only) (WAEC)

Read lesson note on Acids, Bases And Salts (Ghana Only) (WAEC)

Read lesson note on Periodic Chemistry (Ghana Only) (WAEC)

Chemical Bonds (Ghana Only)

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Question 28 Report

In the laboratory preparation of oxygen, dried oxygen is usually collected over

hydrochloric acid

mercury Correct answer

calcium chloride

tetraoxosulphate (VI) acid

Answer Details

Read lesson note on Acids, Bases And Salts (Ghana Only) (WAEC)

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Question 29 Report

How many cations will be produced from a solution of potassium aluminium tetraoxosulphate (VI)?

2 Correct answer

Answer Details

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Question 30 Report

Which of the following is a deliquescent compound?

Na2CO3

CaCl2 Correct answer

CuO

Na2CO3.10H2O

Answer Details

A deliquescent compound is a compound that readily absorbs moisture from the atmosphere and forms a solution. From the given options, only CaCl2 is a deliquescent compound. Therefore, the answer is CaCl2.

Read lesson note on Acids, Bases And Salts (Ghana Only) (WAEC)

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Question 31 Report

Choose the correct answer in the option above.

Which of the following is a primary amine?

B Correct answer

Answer Details

Read lesson note on Chemistry Of Carbon Compounds (Ghana Only) (WAEC)

Chemistry Of Carbon Compounds (Ghana Only)

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Question 32 Report

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

move at different speeds in the column Correct answer

dissolve in each other in the column

react with the solvent in the column

react with each other in the column

Answer Details

The principle of column chromatography is based on the ability of the constituents to move at different speeds in the column. In column chromatography, a mixture is passed through a column containing a stationary phase (e.g. silica gel) and a mobile phase (e.g. solvent). Different constituents of the mixture have different affinities for the stationary and mobile phases, and thus move at different speeds through the column. This allows them to be separated based on their different physical and chemical properties.

Read lesson note on Separation Of Mixtures And Purification Of Chemical Substances (JAMB)

Separation Of Mixtures And Purification Of Chemical Substances

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Question 33 Report

In the diagram above, X is the

enthalpy

enthalpy change Correct answer

activation energy

activated complex

Answer Details

Read lesson note on Oxidation And Reduction (JAMB)

Read lesson note on Energy Changes (JAMB)

Oxidation And Reduction

Energy Changes

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Question 34 Report

The compound above exhibits

geometric isomerism

optical isomerism Correct answer

structural isomerism

positional isomerism

Answer Details

Read lesson note on Chemistry Of Carbon Compounds (Nigeria Only) (WAEC)

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Question 35 Report

From the diagram above, an ideal can be represented by

N Correct answer

Answer Details

Read lesson note on Structure Of The Atom (WAEC)

Read lesson note on Atomic Structure And Bonding (JAMB)

Structure Of The Atom

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Question 36 Report

A few drops of concentrated HNO3 is added to an unknown solution and boiled for a while. If this produces a brown solution, the cation presents is likely to be

Pb2+

Cu2+

Fe3+

Fe2+ Correct answer

Answer Details

Read lesson note on Chemical Bonds (Ghana Only) (WAEC)

Read lesson note on Periodic Chemistry (Ghana Only) (WAEC)

Chemical Bonds (Ghana Only)

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Question 37 Report

An effect of thermal pollution on water bodies is that the

volume of water reduces

volume of chemical waste increase

level of oxides of nitrogen increase

level of oxygen reduces Correct answer

Answer Details

Thermal pollution refers to the sudden increase or decrease in the temperature of water bodies due to human activities. An effect of thermal pollution on water bodies is that the level of oxygen reduces. This happens because warm water cannot hold as much oxygen as cooler water, so as the temperature rises, the amount of oxygen in the water decreases. This can lead to a decrease in the number of fish and other aquatic organisms that require oxygen to survive. Additionally, thermal pollution can also cause changes in the ecosystem and affect the balance of aquatic life.

Read lesson note on Environmental Pollution (JAMB)

Environmental Pollution

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Question 38 Report

A suitable solvent for iodine and nephthalene is

carbon (IV) sulphide

ethanol Correct answer

water

benzene

Answer Details

Read lesson note on Solubility (JAMB)

Solubility

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Question 39 Report

The bleaching action of chlorine gas is effective due to the presence of

hydrogen chloride

water Correct answer

air

oxygen

Answer Details

Chlorine gas is a strong oxidizing agent, which means it can take electrons from other substances. When chlorine gas is dissolved in water, it reacts with the water molecules to form hypochlorous acid and hydrochloric acid. Hypochlorous acid is a powerful oxidizing agent and can break down the color molecules in stains, thus "bleaching" them. Therefore, the bleaching action of chlorine gas is effective due to the presence of water.

Read lesson note on Acids, Bases And Salts (JAMB)

Acids, Bases And Salts

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Question 40 Report

Hardness of water is mainly due to the presence of

calcium hydroxide or magnesium hydroxide

calcium trioxocarbonate (IV) or calcium tetraoxosulphate (VI) Correct answer

sodium hydroxide or magnesium ydroxide

calcium chloride or sodium chloride salts

Answer Details

Read lesson note on Oxidation And Reduction (JAMB)

Oxidation And Reduction

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Question 41 Report

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

water and carbon (IV) oxide

water, carbon (IV) oxide and oxygen

oxygen and carbon (IV) oxide

water and oxygen Correct answer

Answer Details

Corrosion is a process that occurs when a metal is exposed to its environment, and it results in the gradual destruction or deterioration of the metal. The condition required for corrosion to take place is the presence of water and oxygen. The presence of carbon (IV) oxide may also contribute to the process, but it is not necessary for corrosion to occur. When metal is exposed to air and moisture, a chemical reaction occurs between the metal and the oxygen in the air, which produces metal oxide. This metal oxide is what causes the corrosion of the metal.

Read lesson note on Air (JAMB)

Read lesson note on Periodic Chemistry (Ghana Only) (WAEC)

Air

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Question 42 Report

The constituents of baking powder that makes the dough to rise is

NaHCO3 Correct answer

NaOH

Na2CO3

NaCl

Answer Details

Baking powder is a leavening agent used in baking that helps the dough to rise by releasing carbon dioxide gas when it reacts with moisture and heat. The main constituents of baking powder are baking soda (sodium bicarbonate) and an acid (usually cream of tartar). When these two ingredients are mixed with a small amount of cornstarch to prevent clumping, it forms baking powder. When baking powder is added to the dough, the baking soda and acid react with each other in the presence of moisture and heat. This reaction produces carbon dioxide gas, which gets trapped in the dough and causes it to rise. Therefore, the correct option from the given list is NaHCO3, which is baking soda (sodium bicarbonate), the primary ingredient responsible for making the dough rise in baking powder.

Read lesson note on Acids, Bases And Salts (JAMB)

Acids, Bases And Salts

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Question 43 Report

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

They are members of the same homologous series Correct answer

They have the same boiling point

They have different number of carbon atoms

They have the same chemical properties

Answer Details

2-methylpropane and butane are both hydrocarbons, but they differ in their structures. 2-methylpropane has a branched chain structure while butane has a straight chain structure. 1. The statement "They are members of the same homologous series" is true. They both belong to the alkane homologous series, which is characterized by hydrocarbons with only single covalent bonds. 2. The statement "They have the same boiling point" is false. Boiling points of hydrocarbons increase as the number of carbon atoms in the molecule increases. Butane has a higher boiling point than 2-methylpropane because it has more carbon atoms in its structure, and therefore has stronger intermolecular forces of attraction. 3. The statement "They have different number of carbon atoms" is true. Butane has four carbon atoms in its structure while 2-methylpropane has only three. 4. The statement "They have the same chemical properties" is false. While they both belong to the same homologous series and have similar chemical properties, their different structures affect their reactivity. For example, 2-methylpropane may undergo different reactions than butane due to the presence of a branching in its structure.

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Question 44 Report

The relative atomic mass of a naturally occurring lithium consisting of 90% Li and 10% Li is

6.9

7.1

6.2 Correct answer

6.8

Answer Details

The relative atomic mass of an element is the average mass of all the isotopes of that element, taking into account their natural abundance. Lithium has two naturally occurring isotopes: lithium-6 and lithium-7. The first isotope, lithium-6, makes up 90% of naturally occurring lithium, while the second isotope, lithium-7, makes up the remaining 10%. To find the relative atomic mass of this mixture of isotopes, we need to take the weighted average of their atomic masses, where the weights are their natural abundances. The atomic mass of lithium-6 is 6 atomic mass units (amu), while the atomic mass of lithium-7 is 7 amu. Using the formula for weighted average, we get: (0.9 x 6 amu) + (0.1 x 7 amu) = 5.4 amu + 0.7 amu = 6.1 amu Therefore, the relative atomic mass of naturally occurring lithium consisting of 90% Li-6 and 10% Li-7 is 6.1 amu, which is closest to option (C) 6.2.

Read lesson note on Atomic Structure And Bonding (JAMB)

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Question 45 Report

An isotope has an atomic number of 15 and a mass number of 31. The number of protons it contains is

15 Correct answer

Answer Details

The atomic number of an element is equal to the number of protons in its nucleus. Therefore, if an isotope has an atomic number of 15, it means it has 15 protons. The mass number of an isotope is equal to the total number of protons and neutrons in its nucleus. The question states that the isotope has a mass number of 31. So, we can write: mass number = number of protons + number of neutrons 31 = 15 + number of neutrons To solve for the number of neutrons, we can subtract 15 from both sides: 31 - 15 = 15 + number of neutrons - 15 16 = number of neutrons Therefore, the isotope with an atomic number of 15 and a mass number of 31 contains 15 protons. Answer is correct.

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Question 46 Report

Which of the following properties is NOT peculiar to matter?

kinetic energy of particles increase from solid to gas

Random motion of particles increases from liquid to gas

Orderliness of particles increases from gas to liquid

Random motion of particles increases from gas to solid Correct answer

Answer Details

Read lesson note on Kinetic Theory Of Matter And Gas Laws (JAMB)

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Question 47 Report

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

give it high tensile strenght

make it malleable and ductile

increase its melting point

lower its melting point Correct answer

Answer Details

The presence of impurities such as carbon and sulphur in iron will lower its melting point. This is because impurities disrupt the regular arrangement of iron atoms, making it more difficult for them to move and reducing the amount of heat energy required for the iron to change from a solid to a liquid state. As a result, the melting point of the iron is decreased, making it easier to melt. It is important to note that while impurities may affect other properties of iron, such as its tensile strength or ductility, the question specifically asks about their effect on the melting point.

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Metals And Their Compounds

Non-metals And Their Compounds

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Question 48 Report

What type of bond exits between an element X with atomic number 12 and Y with atomic number 17?

Electrovalent Correct answer

Metallic

Covalent

Dative

Answer Details

Element X has atomic number 12, which means it has 12 protons in its nucleus. This also means that it has 12 electrons in its neutral state. Element Y has atomic number 17, which means it has 17 protons in its nucleus. This also means that it has 17 electrons in its neutral state. To determine the type of bond between X and Y, we need to look at their electronegativity values. Electronegativity is the tendency of an atom to attract electrons towards itself in a chemical bond. X is a metal element and generally has low electronegativity values, while Y is a non-metal element and generally has high electronegativity values. In this case, since X is a metal element and Y is a non-metal element, we can predict that the bond between them will be an electrovalent or ionic bond. An electrovalent bond is formed when electrons are transferred from a metal to a non-metal element. The metal element becomes positively charged and the non-metal element becomes negatively charged, forming ions. The attraction between the oppositely charged ions forms the electrovalent bond. Therefore, the type of bond that exists between element X with atomic number 12 and Y with atomic number 17 is electrovalent or ionic. Note: The term "electrovalent" is an older term for ionic bonds, which is why the option uses this term.

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Chemical Bonds (Ghana Only)