JAMB UTME - Chemistry - 2003

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Question 4 Report

When at equilibrium, which of the reactions below will shift to the right if the pressure is increased and the temperature is kept constant?

2SO3(g) ? 2SO2(g) + O2(g)

2CO2(g) ? 2CO(g) + O2(g)

2H2(g) + O2(g) ? 2H2O(g) Correct answer

2NO(g) ? N2(g) + O2(g)

Answer Details

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

Chemical Kinetics And Equilibrium Systems (Ghana Only)

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Question 5 Report

Neutral atoms of neon with atomic number 10 have the same number of electron as

O2+

Ca2+

K+

Mg2+ Correct answer

Answer Details

Read lesson note on Atomic Structure And Bonding (JAMB)

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Question 6 Report

Which of the following ions is acidic?

K+

KNO3- Correct answer

S2-

H3O+

Answer Details

Acids are ionic compounds ( a compound with a positive or negative charge) that break apart in water to form a hydrogen ion (H+).

For example: NaCl, KNO3, CaBr2, CsClO4

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

Acids, Bases And Salts

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Question 7 Report

How many isomers does pentane have?

3 Correct answer

Answer Details

Pentane is a hydrocarbon with a chemical formula of C5H12, which means it has five carbon atoms and 12 hydrogen atoms. The carbon atoms in pentane can be arranged in different ways, which results in different structures with the same chemical formula. These different structures are called isomers. In the case of pentane, there are three types of isomers: 1. Straight-chain pentane: This is the most basic isomer of pentane, with all five carbon atoms arranged in a straight line. 2. Branched-chain pentane: In this isomer, the carbon atoms are arranged in a branched structure. 3. Cyclopentane: This isomer has a ring structure, with the five carbon atoms arranged in a closed loop. Therefore, pentane has 3 isomers.

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

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Question 8 Report

Which of the following is found in cotton

Starch

Cellulose Correct answer

Fat

Oil

Answer Details

Cotton is a natural fiber that comes from the cotton plant. The main component of cotton fiber is cellulose. Cellulose is a complex carbohydrate made up of glucose molecules, and it is the main structural component of plant cell walls. Therefore, the correct answer to the question is "Cellulose" as it is found in cotton.

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 9 Report

Chlorine gas turns a damp starch-iodide paper

pink

colourless

red

dark blue Correct answer

Answer Details

Chlorine gas turns a damp starch-iodide paper dark blue. This is because the chlorine gas reacts with the iodide ions in the paper to produce iodine, which then reacts with the starch in the paper to form a dark blue complex. This reaction is often used as a test for the presence of chlorine gas.

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

Acids, Bases And Salts (Ghana Only)

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Question 10 Report

When cathode rays are deflected onto the electrode of an electrometer, the instrument becomes

negatively charged Correct answer

positvely charged

neutral

bipolar

Answer Details

When cathode rays, which are negatively charged, are deflected onto the electrode of an electrometer, the instrument becomes negatively charged. This is because the cathode rays are negatively charged, and when they come into contact with the electrode of the electrometer, they transfer some of their negative charge to the electrode, causing it to become negatively charged as well. As a result, the deflection of cathode rays towards the electrode of the electrometer can be measured and detected.

Read lesson note on Atomic Structure And Bonding (JAMB)

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Question 11 Report

Which of the following will change when a catalyst is added to a chemical reaction?

The activation energy Correct answer

The potential energy of the reactants

The heat of the reaction

the potential energy of the product

Answer Details

When a catalyst is added to a chemical reaction, the activation energy of the reaction is reduced. This means that less energy is required to start the reaction and the reaction will proceed at a faster rate. A catalyst does not affect the potential energy of the reactants or products, as these are determined by the nature of the reactants and products themselves. The heat of the reaction is also not affected by the presence of a catalyst, as the amount of heat released or absorbed by a reaction depends on the difference in potential energy between the reactants and products, which remains the same with or without a catalyst. Therefore, the correct answer is The activation energy.

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

Chemical Kinetics And Equilibrium System (Nigeria Only)

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Question 12 Report

The formula for ethyl butanoate is

C3H7COOC2H5 Correct answer

C2H5COOC3H7

C4H9COOC2H5

C2H5COOC4H9

Answer Details

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

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Question 13 Report

The principal constituent of natural gas is

methane Correct answer

ethane

propane

butane

Answer Details

The principal constituent of natural gas is methane. Natural gas is a fossil fuel that is primarily made up of methane gas, along with small amounts of other hydrocarbons like ethane, propane, and butane. Methane is a simple molecule that consists of one carbon atom and four hydrogen atoms. It is a colorless, odorless gas that is highly flammable and is widely used as a fuel for heating, cooking, and electricity generation.

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

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Question 14 Report

The modern process of manufacturing steel for iron is by

treatment with acids

oxidation

blast reduction Correct answer

treatment with alkanal

Answer Details

The modern process of manufacturing steel from iron involves a process called "blast reduction." In this process, iron is heated in a blast furnace with a mixture of carbon and oxygen to remove impurities and create steel. The carbon and oxygen react with the impurities to form carbon dioxide and other gases, which are then released. The result is pure, high-quality steel that can be used for a variety of applications. The other options, treatment with acids or alkanal, and oxidation, are not part of the process of manufacturing steel from iron.

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Chemical Combination

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Question 15 Report

A consequence of global warming is

air pollution

water pollution

increased humudity

flooding Correct answer

Answer Details

Read lesson note on Environmental Pollution (JAMB)

Environmental Pollution

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Question 16 Report

Which of the following statements is true of sulphur (IV) oxide?

It forms tetraoxosulphate (VI) acid with water

It is an odourless gas

It is an acid hybride Correct answer

It forms white precipitate with acidified barium chloride

Answer Details

Sulphur (IV) oxide is a gas that has a pungent odor. It is an acidic oxide that reacts with water to form sulphurous acid. Therefore, the statement that is true of sulphur (IV) oxide is: "It is an acid hydride".

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

Acids, Bases And Salts

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Question 17 Report

The type of reaction that is peculiar to benzene is

addition

hydrolysis

polymerization

substitution Correct answer

Answer Details

The type of reaction that is peculiar to benzene is substitution. Benzene undergoes substitution reactions, in which one or more hydrogen atoms on the benzene ring are replaced by other atoms or groups of atoms. This is due to the special electronic structure of the benzene ring, which makes it particularly stable and resistant to addition or polymerization reactions. Substitution reactions can occur via different mechanisms, such as electrophilic substitution and nucleophilic substitution, and are used to synthesize a wide variety of compounds with diverse properties and applications.

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

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Question 18 Report

The process by which atoms are rearranged into different molecular structure in the petroleum refining process is referred to as

catalytic cracking

hydrocracking

polymerization

reforming Correct answer

Answer Details

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Question 19 Report

The filter in the cigarette reduces the nicotine content by

Burning

Adsorption Correct answer

Evaporation

Absorption

Answer Details

The filter in a cigarette reduces the amount of nicotine that a person inhales through a process called absorption. As the smoke passes through the filter, the chemicals in the filter attract and trap some of the nicotine particles. This results in a lower nicotine content in the smoke that reaches the smoker's lungs. The other options listed, burning, adsorption, and evaporation, do not directly contribute to the reduction of nicotine content in the smoke.

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

Acids, Bases And Salts

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Question 20 Report

If an equilibrium reaction has ∆H < O, the reaction will proceed favorably in the forward reaction at?

low temperatures Correct answer

high temperatures

all temperatures

all pressures

Answer Details

If an equilibrium reaction has a negative value for enthalpy change (∆H < 0), it means that the forward reaction is exothermic and releases heat. According to Le Chatelier's principle, when heat is added to a system at equilibrium, the equilibrium shifts in the direction that absorbs heat. Thus, when the forward reaction is exothermic, it will proceed favorably in the forward direction at low temperatures since the system will shift in the direction that absorbs heat, which in this case is the forward direction. Therefore, the correct option is "low temperatures."

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

Read lesson note on Chemical Equilibria (JAMB)

Chemical Equilibria

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Question 21 Report

Farmlands affected by crude-oil spillage can be decontaminated by

Adding acidic solution

Using aerobic bacteria Correct answer

Pouring water on the affected water area

Burning off the oil from the area

Answer Details

Farmlands affected by crude-oil spillage can be decontaminated by using aerobic bacteria. When crude oil spills occur, they cause harm to the environment by contaminating the soil and water, and this affects the plants and animals. However, some bacteria feed on the components of crude oil, which is a natural process of biodegradation. These bacteria can be used to clean up the affected area by breaking down the crude oil into simpler and less harmful substances. This process is called bioremediation, and it is an effective way of decontaminating farmlands affected by crude-oil spillage.

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

Read lesson note on Environmental Pollution (JAMB)

Chemistry, Industry And The Environment

Environmental Pollution

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Question 22 Report

What mass of K2CrO4 is required to prepare 250cm3 of 0.020 mol dm3 solution?

[K2CrO4 = 194.2g mol-1]

0.97g Correct answer

9.70g

19.42g

97.10g

Answer Details

The problem is asking for the mass of K2CrO4 needed to make a 0.020 mol dm^-3 solution with a volume of 250 cm^3. To solve the problem, we need to use the formula: mass = moles x molar mass First, we need to calculate the number of moles of K2CrO4 needed. We can do this using the formula: moles = concentration x volume Substituting the given values, we get: moles = 0.020 mol dm^-3 x 0.250 dm^3 moles = 0.005 mol Next, we need to find the molar mass of K2CrO4, which is given as 194.2 g mol^-1. Finally, we can calculate the mass of K2CrO4 needed using the formula: mass = moles x molar mass mass = 0.005 mol x 194.2 g mol^-1 mass = 0.971 g Therefore, the mass of K2CrO4 needed to prepare 250 cm^3 of 0.020 mol dm^-3 solution is 0.97 g. Option A, 0.97g, is the correct answer.

Read lesson note on Stoichiometry And Chemical Reactions (WAEC)

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Question 23 Report

The metal that liberates hydrogen from cold water in bubbles only is

Ca Correct answer

Answer Details

Read lesson note on Metals And Their Compounds (JAMB)

Read lesson note on Water (JAMB)

Metals And Their Compounds

Water

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Question 24 Report

If y is an oxidizing agent that reacts with a reducing agent, Z, which of the following is correct?

Y increases in oxidation number

Y becomes reduced Correct answer

Z loses protons

Z gains protons

Answer Details

When an oxidizing agent reacts with a reducing agent, the oxidizing agent causes the reducing agent to lose electrons. This means that the oxidizing agent itself becomes reduced (gains electrons) while the reducing agent becomes oxidized (loses electrons). Therefore, the correct answer to the question is "Y becomes reduced", since y is the oxidizing agent in this scenario. The other answer options are incorrect because they do not describe the expected outcome of the reaction between an oxidizing agent and a reducing agent.

Read lesson note on Oxidation And Reduction (JAMB)

Oxidation And Reduction

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Question 25 Report

When 10g of sodium hydroxide is dissolved in 1000cm3 of water, the sodium formed is approximately

[Na = 23, H = 1, O = 16]

0.01 mol dm-3

0.10 mol dm-3

0.25 mol dm-3 Correct answer

0.50 mol dm-3

Answer Details

When sodium hydroxide (NaOH) is dissolved in water, it dissociates to form sodium ions (Na+) and hydroxide ions (OH-). The balanced chemical equation for this process is: NaOH (s) → Na+ (aq) + OH- (aq) From the question, we are given that 10g of NaOH is dissolved in 1000 cm3 (or 1 dm3) of water. We can calculate the number of moles of NaOH present in the solution using its molar mass: Molar mass of NaOH = 23 + 16 + 1 = 40 g/mol Number of moles of NaOH = mass ÷ molar mass = 10 ÷ 40 = 0.25 mol Since NaOH dissociates to form one Na+ ion for every NaOH molecule, the number of moles of Na+ ions produced is also 0.25 mol. The volume of the solution is 1000 cm3 (or 1 dm3), so the concentration of sodium ions can be calculated as follows: Concentration of Na+ ions = number of moles ÷ volume of solution = 0.25 ÷ 1 = 0.25 mol dm-3 Therefore, the correct answer is "0.25 mol dm-3".

Read lesson note on Stoichiometry And Chemical Reactions (WAEC)

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Question 26 Report

What volume of oxygen is produced from the decomposition of 2 mole of KCIO3 at s.t.p?

[Molar volume of a gas at s.t.p = 22.4 dm3]

22.4 dm3

33.6 dm3

44.8 dm3

67.2 dm3 Correct answer

Answer Details

The question is asking for the volume of oxygen produced from the decomposition of 2 moles of KCIO3 at s.t.p, given the molar volume of a gas at s.t.p is 22.4 dm3. Firstly, we need to balance the chemical equation for the decomposition of KCIO3: 2KClO3 → 2KCl + 3O2 From the equation, we can see that for every 2 moles of KCIO3, we get 3 moles of O2. Therefore, to find the volume of oxygen produced, we can use the following calculation: Volume of O2 = number of moles of O2 × molar volume of a gas at s.t.p Volume of O2 = 3 mol × 22.4 dm3/mol Solving this equation gives us: Volume of O2 = 67.2 dm3 So the answer is 67.2 dm3. Therefore, the label for the question would be "stoichiometry" and "gas volume calculations".

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

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Question 27 Report

Hydrogen can be displaced from a hot alkaline solution by

Fe Correct answer

Answer Details

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

Acids, Bases And Salts

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Question 28 Report

3Cu + pHNO3 →3Cu(NO)2 + 4H2 O + xNO

In the equation above, the values of p and x respectively are

1 and 3

2 and 3

6 and 2

8 and 2 Correct answer

Answer Details

The chemical equation given shows the reaction between copper and nitric acid. The balanced equation is: 3Cu + 8HNO3 → 3Cu(NO3)2 + 2NO + 4H2O. Therefore, the values of p and x respectively are 8 and 2. The coefficient 8 shows that eight moles of nitric acid (HNO3) are required to react with three moles of copper (Cu), and the coefficient 2 shows that two moles of nitrogen monoxide (NO) are produced as one of the products.

Read lesson note on Stoichiometry And Chemical Reactions (WAEC)

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Question 29 Report

A change in the temperature of a saturated solution disturbs the equilibrium between the

Undissolved solute and the solvent

Dissolved solute and the solvent

Dissolved solute and the undissolved solute Correct answer

Dissolved solute and the solution

Answer Details

When a substance dissolves in a solvent, it establishes an equilibrium between the dissolved solute and the undissolved solute. Temperature is a factor that affects this equilibrium. As temperature changes, the solubility of the solute may change, which can affect the concentration of the dissolved solute in the solution. Therefore, a change in temperature of a saturated solution can disturb the equilibrium between the dissolved solute and the solvent. Answer: Dissolved solute and the solvent.

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

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Question 30 Report

The noble gases owe their inactivity to

Octet configuration Correct answer

Cyclic shape

Hexagonal shape

Obtuse configuration

Answer Details

The noble gases are a group of chemical elements in the periodic table, including helium, neon, argon, krypton, xenon, and radon. They are called noble gases because they are very unreactive and rarely participate in chemical reactions. This is due to their electronic configuration, which already has a full outermost shell of electrons (also called an octet configuration). This means they do not need to gain or lose electrons to achieve stability, unlike other elements. Therefore, the noble gases are stable and do not readily react with other elements to form compounds. So, the answer to the question is: Octet configuration.

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Structure Of The Atom

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Question 31 Report

What is the percentage by mass of oxygen in Al2(SO4)3. 2H2O?

[Al = 27, S = 32, H = 1, O = 16]

14.29%

25.39%

50.79%

59.25% Correct answer

Answer Details

To calculate the percentage by mass of oxygen in Al2(SO4)3.2H2O, we need to find the total mass of the compound and the mass of oxygen in the compound. First, let's calculate the total mass of the compound: 2 atoms of Al x 27 g/mol = 54 g/mol 3 atoms of S x 32 g/mol = 96 g/mol 14 atoms of O x 16 g/mol = 224 g/mol 4 atoms of H x 1 g/mol = 4 g/mol Total mass = 54 + 96 + 224 + 4 = 378 g/mol Next, let's calculate the mass of oxygen in the compound: 14 atoms of O x 16 g/mol = 224 g/mol Now we can calculate the percentage by mass of oxygen in the compound: (Mass of oxygen / Total mass) x 100% = (224 g/mol / 378 g/mol) x 100% = 59.25% Therefore, the answer is 59.25%.

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

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Question 32 Report

A compound contains 40.0% carbon 6.7% hydrogen and 53.3% oxygen. If the molar mass of the compound is 180, find the molecular formula.

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

CH2O

C3H6O3

C6H12O6 Correct answer

C6H12O3

Answer Details

The compound is made up of 40.0% carbon, 6.7% hydrogen, and 53.3% oxygen. We need to find the molecular formula of the compound. The first step is to calculate the empirical formula by converting the percentages to mole ratios. To do this, we assume that we have 100 grams of the compound, so we have 40.0 grams of carbon, 6.7 grams of hydrogen, and 53.3 grams of oxygen. Then we convert each of these masses to moles using their respective molar masses: - Carbon: 40.0 g * (1 mol / 12.0 g) = 3.33 mol - Hydrogen: 6.7 g * (1 mol / 1.0 g) = 6.7 mol - Oxygen: 53.3 g * (1 mol / 16.0 g) = 3.33 mol Next, we divide each of these mole values by the smallest of the three, which is 3.33 mol: - Carbon: 3.33 mol / 3.33 mol = 1 - Hydrogen: 6.7 mol / 3.33 mol ≈ 2 - Oxygen: 3.33 mol / 3.33 mol = 1 This gives us an empirical formula of CH2O. To find the molecular formula, we need to know the actual molar mass of the compound. The problem states that the molar mass is 180 g/mol. To find the molecular formula, we divide the molar mass by the empirical formula mass: - Empirical formula mass: 12.0 g/mol (C) + 2.0 g/mol (H) + 16.0 g/mol (O) = 30.0 g/mol - Molecular formula mass: 180 g/mol / 30.0 g/mol = 6 So the molecular formula is some multiple of the empirical formula. From the options provided, we can see that has the correct ratio of atoms: C6H12O6. Therefore, the molecular formula of the compound is C6H12O6.

Read lesson note on Stoichiometry And Chemical Reactions (WAEC)

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Question 33 Report

A liquid that will dissolve fat is

Hydrochloric acid

Calcium hydroxide

Kerosene Correct answer

Water

Answer Details

A liquid that can dissolve fat is typically a nonpolar solvent, meaning it does not have a strong electrical charge. This is because fat molecules themselves are nonpolar and do not dissolve easily in polar solvents like water.
Out of the given options, kerosene is the only nonpolar solvent, and therefore the only option that could potentially dissolve fat. Hydrochloric acid and calcium hydroxide are polar solvents, and water is a highly polar solvent, and would not be able to dissolve fat.

Read lesson note on Solubility (JAMB)

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

Solubility

Acids, Bases And Salts (Ghana Only)

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Question 34 Report

Metals of the first transition series have special properties which are different from those of groups I and II elements because they have partially filled

S orbital

P orbital

D orbital Correct answer

F orbital

Answer Details

Metals of the first transition series have unique properties because they have partially filled D orbitals. Unlike groups I and II elements that have completely filled s orbitals, transition metals have partially filled d orbitals which makes them good conductors of electricity, have high melting and boiling points, are malleable and ductile, and are able to form compounds with different oxidation states. The partially filled d orbitals allow for the formation of complex ions and compounds, which can exhibit interesting and useful properties.

Read lesson note on Atomic Structure And Bonding (JAMB)

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Question 35 Report

The leachate of a certain plant ash is used in local soap making because it contains

sodium chloride and potassium hydroxide

sodium hydroxide Correct answer

potassium hydroxide

soluble carbonates and hydrogen carbonates

Answer Details

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

Acids, Bases And Salts

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Question 36 Report

Ethene reacts with hydrogen bromide to give

CH2Br2

CH3CH2Br Correct answer

C2H2Br2

CHBr2

Answer Details

When ethene (C2H4) reacts with hydrogen bromide (HBr), it undergoes an addition reaction to form a haloalkane. Specifically, the hydrogen (H) of HBr adds to one carbon of the ethene, and the bromine (Br) adds to the other carbon, resulting in the formation of a monobromoalkane. The correct answer is therefore: - CH3CH2Br (or C2H5Br) (CH2Br2) is incorrect as it represents dibromomethane, which is not the expected product of the reaction. (CH3CHBr2) is incorrect as it represents dibromoethane, which is also not the expected product of the reaction. (C2H2Br2) is incorrect as it represents 1,2-dibromoethene, which is a dihaloalkene and also not the expected product of the reaction. Therefore, the correct answer is.

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

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Question 37 Report

Ethanol reacts with excess acidified K2Cr2O to produce

ethanedioic acid

ethanal

ethylethanoate

ethanoic acid Correct answer

Answer Details

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

Acids, Bases And Salts

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Question 38 Report

I. \( \mathrm{H} = 1s^1 \) II. \( \mathrm{N} = 1s^2\,2s^2\,p^3 \) III. \( \mathrm{O} = 1s^2\,2s^2\,p^4 \) IV. \( \mathrm{Zn} = 1s^2\,2s^2\,2p^6\,3s^2\,3p^6\,4s^2\,3d^{10} \)

From the above, which of the following pairs is like to be paramagnetic?

I and II Correct answer

I and III

I and IV

III and IV

Answer Details

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Question 39 Report

CO(g) + H2O(g) ? CO2(g) + H2(g)

From the reaction above, calculate the standard enthalpies of formation of CO2(g), H2O(g) and CO(g) in kJ mol-1 are -394, -242, and -110 respectively.

-262 kJ mol-1

-42 kJ mol-1 Correct answer

+42 kJ mol-1

+262 kJ mol-1

Answer Details

CO + H2O ? CO2 + H2 DH = 394 kJ mol-1
-242 + 110 = -352 kJ mol-1
35 = -394 -(352)
= -394 + 352
= -42 kJ mol-1

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

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Question 40 Report

In the electrolysis of a concentrated solution of sodium chloride using electrodes, which of the following ions are discharged at the cathode and anode respectively?

Na+ and Cl-

Na+ and OH-

H+ and OH-

H+ and Cl- Correct answer

Answer Details

Read lesson note on Rates Of Chemical Reaction (JAMB)

Read lesson note on Electrolysis (JAMB)

Rates Of Chemical Reaction

Electrolysis

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Question 41 Report

The salt that will form a precipitate soluble in excess ammonia solution is

Ca(NO3)2

Cu(NO3)2 Correct answer

Mg(NO3)2

Al(NO3)3

Answer Details

The question is asking which of the given salts will form a precipitate that is soluble in excess ammonia solution. When a salt is soluble in water, it dissolves completely in water, forming a clear solution. When a salt is insoluble in water, it does not dissolve in water, forming a precipitate. In this case, the question is asking for a salt that will form a precipitate that is soluble in excess ammonia solution. To answer the question, we need to know which of the given salts will react with excess ammonia solution to form a complex ion that is soluble in water. The only salt among the given options that will do this is copper (II) nitrate, Cu(NO3)2. When excess ammonia solution is added to copper (II) nitrate, a deep blue complex ion, [Cu(NH3)4]2+, is formed, which is soluble in water. The other salts among the given options will form precipitates that are insoluble in excess ammonia solution. Therefore, the salt that will form a precipitate soluble in excess ammonia solution is copper (II) nitrate, Cu(NO3)2.

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

Acids, Bases And Salts

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Question 42 Report

The weakest attractive force that can be observed between two molecules is

ionic

covalent

coordinate covalent

van der Waals Correct answer

Answer Details

The weakest attractive force that can be observed between two molecules is van der Waals force. Van der Waals force is a weak electrostatic attraction that exists between the positive and negative charges of two adjacent molecules. This force arises due to the fluctuations in the electron cloud around the atoms in the molecule. While ionic, covalent, and coordinate covalent bonds involve the transfer or sharing of electrons between atoms to form a strong attraction, van der Waals force is a relatively weak attraction between two molecules.

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

Read lesson note on Atomic Structure And Bonding (JAMB)

Chemical Bonds (Ghana Only)

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Question 43 Report

Chlorine gas is prepared in the laboratory by

adding concentrated hydrochloric acid to solid manganese (IV) oxide Correct answer

aciding concentrated tetraoxosulphate (VI) acid to solid sodium chloride

dropping concentrated hydrochloric acid onto potassium tetraoxomanganate (VI) crystals

aciding concentrated tetraoxosulphate (VI) acid to hydrochloric acid

Answer Details

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

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Question 44 Report

A gas exerts pressure on its container because

some of its molecules are moving faster than others

of the collision of the molecules with each other

of the mass of the molecules of gas

the molecules of a gas colide with the walls of the container Correct answer

Answer Details

A gas exerts pressure on its container because the molecules of the gas collide with the walls of the container. As gas molecules move randomly and collide with each other and with the walls of the container, they exert a force on the walls. This force per unit area is defined as pressure. Therefore, the pressure exerted by a gas is the result of the constant collisions of the gas molecules with the walls of the container. The other options given are not correct explanations for why a gas exerts pressure on its container.

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

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Question 45 Report

Which of the following is physical change?

Burning kerosene

Freezing ice cream Correct answer

Exposing white phosphorus

Dissolving calcium in water

Answer Details

A physical change is a change in which the chemical composition of the substance remains the same. In other words, the substance doesn't change its identity. Burning kerosene is a chemical change because it reacts with oxygen to produce carbon dioxide and water vapor. Exposing white phosphorus to air is a chemical change because it reacts with oxygen to form a white powder of phosphorus pentoxide. Dissolving calcium in water is a chemical change because it produces hydrogen gas and forms calcium hydroxide. Freezing ice cream is a physical change because the liquid cream changes into a solid state due to the decrease in temperature, but the chemical composition of the ice cream remains the same. Therefore, the answer is "Freezing ice cream".

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States Of Matter

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Question 46 Report

The commonest feature of reactions at the anode is that

electrons are consumed

oxidation is involved Correct answer

ions are reduced

electrode dissolves

Answer Details

The anode is the electrode where oxidation takes place during a chemical reaction. Oxidation involves the loss of electrons by a substance. Therefore, the commonest feature of reactions at the anode is that oxidation is involved. The substance being oxidized loses electrons and becomes positively charged, while the electrons are transferred to the cathode, where reduction takes place. So, the correct answer is oxidation is involved.

Read lesson note on Oxidation And Reduction (JAMB)

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

Oxidation And Reduction

SOLUBILITY OF SUBSTANCES (Nigeria Only)

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Question 47 Report

Which of the following is an electrolyte?

alcohol

sodium ethanoate Correct answer

solid potassium hydroxide

mercury

Answer Details

Read lesson note on Electrolysis (JAMB)

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

Electrolysis

Acids, Bases And Salts (Ghana Only)

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Question 48 Report

According to the kinetic theory, an increase in temperature causes the kinetic energy of particles to

Decrease

Increase Correct answer

Remain constant

Be zero

Answer Details

According to the kinetic theory of matter, all matter is made up of particles that are in constant motion. The kinetic energy of a particle is the energy it possesses due to its motion. An increase in temperature means that the average kinetic energy of the particles in a substance increases. So, when the temperature of a substance increases, the kinetic energy of its particles also increases. Therefore, the correct answer is "Increase".

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