WAEC SSCE - Chemistry - 2004 (Objective)

Question 1 Report

What of the following pairs of acid and base will produce a solution with pH less than 7 at equivalence point?

HNO₃ and NaOH

H₂SO₄ and KOH

HCI and Mg(OH) ₂ Correct answer

HNO ₃ and KOH

Answer Details

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Acids, Bases And Salts

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Question 2 Report

Which of the following subtances will not produce effervescence with dilute hydeochloric acid?

Copper (ll) trioxocarbonate (IV)

Potassium hydrogentrioxocarbonate (lV)

Zinc granules

Sodium chloride Correct answer

Answer Details

Sodium chloride will not produce effervescence with dilute hydrochloric acid. When a substance reacts with dilute hydrochloric acid, it produces bubbles of carbon dioxide gas, which causes effervescence. Copper (II) trioxocarbonate (IV), potassium hydrogen trioxocarbonate (IV), and zinc granules are all carbonates that react with hydrochloric acid to produce carbon dioxide gas and effervescence. Sodium chloride, on the other hand, is a halide that does not react with hydrochloric acid, and therefore does not produce effervescence.

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Solubility

Metals And Their Compounds

Acids, Bases And Salts

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Question 3 Report

When ammonium trioxocarbonate (IV) solution is added to separate solutions of calcium, zinc and sodium salt precipitate could be formed in the case of

calcium only

zinc only

calcium and znic only Correct answer

sodium and zinc only

Answer Details

When ammonium trioxocarbonate (IV) solution is added to separate solutions of calcium, zinc and sodium salt, precipitates could be formed in the case of calcium and zinc only. The ammonium trioxocarbonate (IV) solution reacts with the calcium and zinc ions in the solutions to form insoluble carbonates as follows: Ca²⁺ + CO₃^2- → CaCO_3(s) Zn²⁺ + CO₃^2- → ZnCO_3(s) These carbonates are insoluble in water and will form precipitates in the solutions. The sodium ion does not react with the ammonium trioxocarbonate (IV) solution and therefore, no precipitate will be formed in its solution.

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Acids, Bases And Salts

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Question 4 Report

Which of the following pollutants is biodegradable?

Domestic sewage Correct answer

Metal scraps

Radioactive waste

Plastic foil

Answer Details

Domestic sewage is biodegradable. Biodegradable means that a substance can be broken down by living organisms such as bacteria, fungi, and other microorganisms. Domestic sewage consists of organic matter such as food waste and human waste, which can be decomposed by microorganisms. The process of decomposition breaks down the organic matter into simpler compounds that can be absorbed by the soil, making domestic sewage a natural fertilizer. Therefore, domestic sewage can be biodegraded by microorganisms in the soil or in wastewater treatment plants.

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Chemistry, Industry And The Environment

Environmental Pollution

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Question 5 Report

The mass of 800cm³ of a gas X at s.t.p. is 1.0g. What is the molar mass of X? [1 mole of a gas at s.t.p occupies 22.4dm ³]

18.0g mol^-1

22.4g mol^-1

28.0gmol^-1 Correct answer

36.0gmol^-1

Answer Details

The molar mass of gas X can be determined by using the formula: molar mass = mass / (volume of gas at stp / molar volume of gas at stp) The mass of the gas X is given as 1.0g and the volume of 800cm³ can be converted to dm³ by dividing by 1000: volume of gas at stp = 800cm³ / 1000 = 0.8dm³ The molar volume of a gas at stp is given as 22.4dm³/mol. Substituting these values into the formula, we get: molar mass = 1.0g / (0.8dm³ / 22.4dm³/mol) molar mass = 1.0g / (0.0357mol) molar mass = 28.0g/mol Therefore, the molar mass of gas X is 28.0g/mol. The correct option is: 28.0gmol^-1.

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Kinetic Theory Of Matter And Gas Laws

Separation Of Mixtures And Purification Of Chemical Substances

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Question 6 Report

Which of the following is required in an experiment to determine the enthalpy of solution of anhydrous CuSO? l. Mass of the anhydrous CuSO ₄ II. Volume of water in which the CuSO₄ is dissolved lll. lnitial temperature of water lV. Final temperature of the solution

l and ll only

lll and IV only

ll, lll, and IV only

l, ll, lll, and IV only Correct answer

Answer Details

To determine the enthalpy of solution of anhydrous CuSO₄, we need to dissolve a known mass of CuSO₄ in a known volume of water, measure the initial temperature of the water and the final temperature of the solution. Therefore, we need all the four options: i.e., l, ll, lll, and IV. We need to know the mass of CuSO₄ used to determine the amount of solute in the solution. The volume of water is required to calculate the concentration of the solution. The initial temperature of the water is required to determine the amount of heat absorbed by the solution, and the final temperature of the solution is required to determine the amount of heat released by the solution.

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Energy Changes

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Question 7 Report

Which of the following factors that affect the rate of chemical reactions can be explained in terms of the collision theory? l. concentration ll. pressure lll. temperature lV catalyst

l and ll only

l, ll and lll only

l and lll only

l, II, lll and IV only Correct answer

Answer Details

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Rates Of Chemical Reaction

Stoichiometry And Chemical Reactions

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Question 8 Report

The condensation of several amino acid molecules gives

long chain alkanoic acids

secondary alkanols

alkanoates

proteins Correct answer

Answer Details

The condensation of several amino acid molecules gives proteins. A protein is a macromolecule composed of one or more chains of amino acid residues. When two amino acids combine, a peptide bond is formed, and the resulting molecule is called a dipeptide. By continued condensation reactions involving many amino acids, a long chain of amino acids is formed, which is a protein. Therefore, option D, "proteins," is the correct answer.

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Chemistry Of Carbon Compounds (Nigeria Only)

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Question 9 Report

Consider the cell represented below: Zn/Zn²⁺_(aq) // Cu²⁺_(aq) / Cu_(s). Which of the following statements is correct about the cell

Zn is oxidized to Zn²⁺ Correct answer

Cu is oxidized to Cu²⁺

It is an electrolytic cell

each single line represents a salt bridge

Answer Details

The correct statement about the cell represented as Zn/Zn²⁺_(aq) // Cu²⁺_(aq) / Cu_(s) is that Zn is oxidized to Zn²⁺. In this cell, the zinc metal (Zn) is the anode, where oxidation occurs. Zn atoms lose electrons to form Zn²⁺ ions, which go into solution as Zn²⁺_(aq). The electrons released in the oxidation of Zn are transferred through the external circuit to the cathode, which is the copper metal (Cu) electrode. The Cu²⁺ ions in solution gain electrons and are reduced to form copper metal, which deposits on the electrode as Cu_(s). The double line in the cell notation represents the salt bridge, which completes the circuit by allowing the flow of ions between the two half-cells. It prevents the mixing of the solutions in the half-cells, which could disrupt the electrochemical reaction. Therefore, the correct option is "Zn is oxidized to Zn²⁺".

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Electrolysis

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Question 10 Report

Glucose gives a brick-red precipitate with Fehling's solution because it is

carbohydrate

an alkanoate

a reducing sugar Correct answer

a non-electrolyte

Answer Details

Glucose gives a brick-red precipitate with Fehling's solution because it is a reducing sugar. Fehling's solution contains copper ions (Cu²⁺) which are reduced to copper (I) oxide (Cu₂O) by reducing sugars. The brick-red precipitate is the copper (I) oxide formed in the reaction. Glucose is a reducing sugar because it has a free aldehyde or ketone functional group that can donate electrons and reduce other substances like the copper ions in Fehling's solution.

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Kinetic Theory Of Matter And Gas Laws

Organic Compounds

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Question 11 Report

What is the IUPAC name of CH₃CH₂COOCH ₃?

Ethylethanoate

Methylethanoate

Methylpropanoate Correct answer

Propylmethanoate

Answer Details

The IUPAC name of CH₃CH₂COOCH ₃ is methyl propanoate. This is because the compound has a methyl group (-CH₃) attached to the third carbon of a propanoic acid (-COOH) molecule, which results in the name "methyl propanoate". The prefix "methyl" indicates the presence of a -CH₃ group, and the suffix "-oate" indicates the presence of an ester functional group (-COO-).

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Chemistry Of Carbon Compounds (Nigeria Only)

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Question 12 Report

One of the characteristics of transition metals is

reducing ability

ductility

ability to conduct electricity

formation of coloured ions Correct answer

Answer Details

One of the characteristics of transition metals is the formation of coloured ions. Transition metals have partially filled d-orbitals, which allow for the absorption and reflection of certain wavelengths of light. When transition metals form ions, the arrangement of electrons in the d-orbitals changes, causing the ion to absorb and reflect different wavelengths of light. This results in the ion having a different colour than the original metal. Therefore, the ability of transition metals to form coloured ions is one of their defining characteristics.

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Metals And Their Compounds

Water

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Question 13 Report

What are the values of x, y and z respectively in the following in the following equation? MnO _2(s) + xHCI_(aq) → MnCI_2(g) + yHO_(l) + zCI_2(g)

4,1,2

1,2,1

2,1,2

4,2,1 Correct answer

Answer Details

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Stoichiometry And Chemical Reactions

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Question 14 Report

The process of seeding during the extraction of aluminium involves the addition of pure AI(OH)₃ crystals in order to

lower the temperature

increase the concentration

facilitate the precipitation of solid Correct answer

reduce the viscosity of the solution

Answer Details

The addition of pure AI(OH)₃ crystals during the extraction of aluminium is called seeding. The purpose of seeding is to facilitate the precipitation of solid Al(OH)₃. When the pure AI(OH)₃ crystals are added, they act as nucleation sites where additional Al(OH)₃ molecules can deposit and grow. This results in the formation of larger and more uniform particles of Al(OH)₃, which can be easily separated from the solution. Therefore, the correct option is "facilitate the precipitation of solid."

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Kinetic Theory Of Matter And Gas Laws

Electrolysis

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Question 15 Report

Which of the following measures is not suitable for controlling water pollution?

treating industrial effluent and domestic sewage before discharge into water

Controlling the use of agrochemicals

recycling industrial and agricultural wastes

burning industrial and agricultural wastes before discharge into water ways Correct answer

Answer Details

Burning industrial and agricultural wastes before discharge into waterways is not a suitable measure for controlling water pollution. Burning of waste can release harmful chemicals and gases into the air, which can contribute to air pollution. Moreover, burning the waste before discharge into water can increase the temperature of the water, which can have negative effects on aquatic life. Therefore, this measure can actually worsen water pollution and is not a recommended solution. The other options such as treating industrial effluent and domestic sewage before discharge into water, controlling the use of agrochemicals, and recycling industrial and agricultural wastes are effective measures for controlling water pollution.

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Environmental Pollution

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Question 16 Report

What quantity of electrons in moles is needed to discharge two moles of aluminum from aluminum oxide (AI ₂O₃)

6 Correct answer

Answer Details

In order to discharge two moles of aluminum from aluminum oxide (Al₂O₃), each Al³⁺ ion in the Al₂O₃ must be reduced to Al metal, which requires the gain of three electrons per Al³⁺ ion. Therefore, for two moles of aluminum, there are 2 x Avogadro's number (6.022 x 10²³) of Al³⁺ ions that need to be reduced, and each of these requires 3 electrons. Thus, the total number of electrons needed is 2 x Avogadro's number x 3 = 3.612 x 10²⁴ electrons, which can be expressed as 6 moles of electrons. Therefore, the correct answer is 6.

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Kinetic Theory Of Matter And Gas Laws

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Question 17 Report

Which of the following salts is not prepared by precipitation?

Lead (ll) trioxocarbonate (lV)

Barium trioxocarbonate (IV)

Sodium trioxocarbnate (IV) Correct answer

Calcium trioxocarbonate (IV)

Answer Details

Sodium trioxocarbonate (IV) is not prepared by precipitation. Precipitation is a process that involves the formation of an insoluble solid from a solution. Lead (II) trioxocarbonate (IV), barium trioxocarbonate (IV), and calcium trioxocarbonate (IV) are all prepared by precipitation reactions. In the case of sodium trioxocarbonate (IV), it is a soluble salt, and it can be obtained by the reaction between sodium hydroxide and carbon dioxide. Thus, it is not prepared by precipitation, and this is the correct answer.

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Acids, Bases And Salts

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Question 18 Report

Which of the following pairs of salts undergo hydrolysis?

AlCI₃ and NH₄CI Correct answer

AICI₃ and NaCI

FeCI₃ and KCI

Na₂SO₄ and K₂ SO₄

Answer Details

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Acids, Bases And Salts

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Question 19 Report

Which of the following equipment is not used to detect radioactivity?

Wilson cloud chamber

Geiger- muller counter

Mass spectrometer Correct answer

Photographic plate

Answer Details

The equipment that is not used to detect radioactivity is the mass spectrometer. A Wilson cloud chamber is a device used to visualize the path of ionizing radiation by producing condensation trails. A Geiger-Muller counter is an instrument used to detect and measure ionizing radiation. A photographic plate can also be used to detect ionizing radiation. However, a mass spectrometer is an analytical instrument used to determine the composition of a sample by separating its components based on their mass-to-charge ratio. It is not specifically designed to detect radioactivity.

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Kinetic Theory Of Matter And Gas Laws

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Question 20 Report

WHICH OF THE FOLLOWING PETROLEUM FRACTIONS YIELDS VASELINE AND PARAFFIN WAX ON REDISTILLATION?

DIESEL OIL

LUBRICATION OIL Correct answer

PETROL

KEROSENE

Answer Details

The petroleum fractions that yield vaseline and paraffin wax on redistillation is kerosene. When crude oil is distilled, it is separated into different fractions based on their boiling points. Kerosene is one of the fractions that is obtained from the distillation of crude oil. Upon redistillation, the kerosene fraction further separates into different components, including vaseline and paraffin wax. Therefore, the correct option is kerosene.

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Solubility Of Substances (Ghana Only)

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Question 21 Report

The alloy used extensively in the building industry is

steel Correct answer

bronze

duralumin

type metal

Answer Details

The alloy used extensively in the building industry is steel. Steel is an alloy of iron and carbon, with small amounts of other elements such as manganese, silicon, and phosphorus. Steel is known for its strength and durability, making it an ideal material for use in the construction of buildings and other structures. It is also a versatile material that can be easily fabricated and formed into various shapes and sizes, making it an ideal choice for a wide range of construction applications.

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Metals And Their Compounds

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Question 22 Report

A metal X forms two chlorides with the formulae XCI₂ and XCI₃. Where is X in the Periodic Table?

Group ll

Group llI

d-block Correct answer

s-block

Answer Details

Metal X forms two chlorides with formulae XCI₂ and XCI₃. The Roman numeral in the name of a metal chloride indicates the charge of the metal ion. The chlorine atom has a fixed charge of -1. Since the formula of XCI₂ has two chlorine atoms, the total charge contributed by the chlorine atoms is -2. Therefore, the charge of the metal ion in XCI₂ must be +2 in order for the compound to be electrically neutral. Likewise, the charge of the metal ion in XCI₃ must be +3 in order for the compound to be electrically neutral. From the above information, we can conclude that the metal X has variable oxidation states of +2 and +3. This means that the metal X must be a transition metal and located in the d-block of the periodic table. Therefore, the correct answer is "d-block."

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Periodic Chemistry (Nigeria Only)

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Question 23 Report

A solution of zinc chloride should not be stored in a container made of

tin

copper

aluminium Correct answer

lead

Answer Details

A solution of zinc chloride should not be stored in a container made of aluminium. This is because zinc chloride is a corrosive substance and reacts with aluminium to form aluminium chloride and zinc metal. This reaction can lead to the weakening and eventual failure of the container, potentially causing a hazardous spill. Therefore, it is important to store zinc chloride in containers made of materials that are resistant to its corrosive properties, such as glass, plastic, or certain types of metals.

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Non-metals And Their Compounds

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Question 24 Report

What is the change in the oxidation number of 1^- in the reaction represented by the following equation? 51 ^-1_(aq) + 6H⁺_(aq) + 1O^-_3(aq) → 31_2(g) + 3H₂O_(l)

-5 to -3

-1 to 0 Correct answer

+ 5 to + 0

-1 to + 2

Answer Details

The oxidation number of an ion is the charge of the ion. The oxidation number of 1^- is -1. In the equation, the reactant 51 ^-1_(aq) is being oxidized because its oxidation number is changing from -1 to 0. Thus, the change in the oxidation number of 1^- is from -1 to 0, which means an increase in oxidation number or a loss of electrons. Therefore, the answer is -1 to 0.

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Kinetic Theory Of Matter And Gas Laws

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Question 25 Report

The method of collection of gases prepared in the laboratory depend on their

odour and atomicity

colour and odour

atomicity and density

solubility and density Correct answer

Answer Details

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Kinetic Theory Of Matter And Gas Laws

Structure Of The Atom

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Question 26 Report

Two solutions containing Pb²⁺ and AI³⁺ respectively can be distingusihed using

NaOH_(aq)

NH_3(aq)

conc. HCI₃

conc. HCI Correct answer

Answer Details

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

Acids, Bases And Salts (Ghana Only)

Periodic Chemistry (Ghana Only)

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Question 27 Report

WHICH OF THE FOLLOWING SALTS IS READILY SOLUBLE IN WATER?

PbCI₂

Pb(NO ₃) ₂ Correct answer

PbSO₄

PbCO ₃

Answer Details

Pb(NO3)2 is readily soluble in water because it is a nitrate salt. Nitrate salts are generally soluble in water. On the other hand, PbCl2, PbSO4 and PbCO3 are insoluble or only slightly soluble in water.

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Acids, Bases And Salts (Ghana Only)

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Question 28 Report

A metal X forms two chlorides with the formulae XCI2 and XCI3. Where is X in the Periodic Table?
What type of bonding exists between X and chlorine in each of the chlorides?

metallic bonding

ionic bonding Correct answer

covalent bonding

dative bonding

Answer Details

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Kinetic Theory Of Matter And Gas Laws

Acids, Bases And Salts

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Question 29 Report

Which of the following reactions will be affected by change in pressure at equilibrium?

X_(g) + Y_(g) ⇌ W_(g) + Z_(g)

X_(g) + 2Y_(g) ⇌W_(g) + Z_(g) Correct answer

2X_(g) ⇌ W_(g) + Z_(g)

2Y_(g) ⇌ W_(g) + Z_(g)

Answer Details

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Chemical Equilibria

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Question 30 Report

Which of the following statements is true of an endothermic reaction? I. Heat is absorbed from the surrounding II. The heat content of the products is more than that of the reactants III. The enthalpy change is positive IV. The surrounding is at a lower temperature than the system.

l only

l and ll only

l,ll and lll only

l, ll, lll and lV Correct answer

Answer Details

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Energy Changes

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Question 31 Report

A nuclide emits a beta-particle (e) in the process, that atomic number

increases by 1 while the mass numer remains constant Correct answer

decreases by 2 while the mass number remains constant

remains constant while the mass number decreases by 2

remains constant while the mass number increases by 1

Answer Details

When a nuclide emits a beta-particle (e), a neutron inside the nucleus is converted into a proton and an electron is emitted. The mass number of the nuclide remains constant because the total number of protons and neutrons in the nucleus remains the same. However, since a neutron is converted into a proton, the atomic number of the nuclide increases by 1, because the atomic number of an element is equal to the number of protons in its nucleus. Therefore, the correct option is: "the atomic number increases by 1 while the mass number remains constant".

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Atomic Structure And Bonding

Chemical Equilibria

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Question 32 Report

What is the product Cx Hy in the following equation? C₁₀H₁₂ → C₈H₁₈ + CxHy

butene

octane

ethene Correct answer

decane

Answer Details

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Chemistry Of Carbon Compounds (Nigeria Only)

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Question 33 Report

The mass of an element is 27 and its atomic number is 13. What is the composition of the nucleus of its atom?

13 electrons and 14 protons

13 neutrons and 14 protons

13 protons and 14 neutrons Correct answer

13 electrons and 14 neutrons

Answer Details

The atomic number of an element is equal to the number of protons in its nucleus. In this case, the atomic number is 13. This means the nucleus of the atom contains 13 protons. The mass number of an element is equal to the number of protons plus the number of neutrons in its nucleus. The mass of the element is given as 27. Therefore, the number of neutrons in the nucleus can be calculated as follows: Number of neutrons = Mass number - Atomic number Number of neutrons = 27 - 13 Number of neutrons = 14 So, the composition of the nucleus of the atom is 13 protons and 14 neutrons. Therefore, the correct option is "13 protons and 14 neutrons".

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Atomic Structure And Bonding

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Question 34 Report

If 60 cm³ of gas is heated from 27^oC TO 50^oC, what is the new volume of the gas at constant pressure?

32.4cm ³

55.7cm³

64.6cm³ Correct answer

111.1cm³

Answer Details

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Kinetic Theory Of Matter And Gas Laws

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Question 35 Report

Which of the electrons in the following orbitals will experience the greatest nuclear attraction?

1s electron of helium Correct answer

1s electron of potassium

23 electron of boron

2s electron of carbon

Answer Details

The nuclear attraction experienced by an electron depends on the distance between the electron and the nucleus and the number of protons in the nucleus. The greater the number of protons in the nucleus, the greater the nuclear attraction experienced by an electron. Therefore, out of the given options, the 1s electron of helium will experience the greatest nuclear attraction since it has the smallest atomic number and the least distance from the nucleus. The 1s electron of potassium will have the least nuclear attraction since it has the largest atomic number and the greatest distance from the nucleus. The 2s electron of carbon and the 2p electron of boron will have intermediate nuclear attraction.

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Atomic Structure And Bonding

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Question 36 Report

Which of the following electron transition results in the emission of energy?

3p to 3s Correct answer

3p to 4p

2s to 2p

1s to 2s

Answer Details

When an electron transitions from a higher energy level to a lower energy level, it releases energy in the form of electromagnetic radiation. The energy of the emitted radiation corresponds to the difference in energy between the two levels involved in the transition. Based on this information, the correct answer to the question is the electron transition from the 3p orbital to the 3s orbital, as this involves a higher energy level (3p) transitioning to a lower energy level (3s), resulting in the emission of energy. The other options involve transitions from lower to higher energy levels, and therefore do not result in the emission of energy.

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Atomic Structure And Bonding

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Question 37 Report

What volume of hydrogen would be left over when 300cm³ of oxygen and 1000cm of hydrogen are exploded in a sealed tube? [2H_2(g) + O_2(g) → 2H₂ O_g]

200 cm³

400 cm³ Correct answer

600cm³

700cm³

Answer Details

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Stoichiometry And Chemical Reactions

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Question 38 Report

Which of the following properties of elements deceases generally across a period in the Periodic Table?

Electronegativy

Electron affinity

Atomic radluc Correct answer

lonlzation energy

Answer Details

The correct answer is "Atomic radius". Across a period in the Periodic Table, the atomic radius generally decreases. This is because, as you move from left to right across a period, the number of protons in the nucleus increases, and the number of energy levels or shells remains the same. This results in a greater attractive force between the positively charged nucleus and the negatively charged electrons in the outermost shell, pulling them closer to the nucleus and hence decreasing the atomic radius.

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Periodic Chemistry (Nigeria Only)

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Question 39 Report

The key factor to be considered in siting a chemical industry is

favourable climatic conditions

the availability of space to store raw materials

its nearness to other industrial establishments

its nearness to the source of raw materials Correct answer

Answer Details

The key factor to be considered in siting a chemical industry is its nearness to the source of raw materials. This is because chemical industries rely heavily on the availability and accessibility of raw materials for production. Therefore, the cost of transportation and logistics of raw materials to the industry should be minimized to increase efficiency and profitability. Additionally, the proximity to raw materials reduces the risks of shortages, delays and damages in transit, and fluctuations in prices. Other factors such as favourable climatic conditions, the availability of space to store raw materials, and nearness to other industrial establishments may be important but are usually secondary.

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Read lesson note on Chemical Industry And Environment (WAEC)

Chemistry, Industry And The Environment

Chemical Industry And Environment

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Question 40 Report

An orange drink concentrate is suspected to contain traces of poisonous green dye and a harmless dye having the same boiling point. Which of the following techniques is most suitable for isolating the dyes?

Fractional distillation

Paper chromatography Correct answer

Coagulation

Recrystallization

Answer Details

Paper chromatography is the most suitable technique for isolating the dyes in the orange drink concentrate. This is because paper chromatography can separate the components of a mixture based on their solubility and polarity, which is exactly what is needed to separate the two dyes. The technique involves placing a small amount of the mixture on a piece of paper and allowing the components to move up the paper as a solvent travels up the paper. The dyes will move at different rates depending on their solubility and polarity, allowing them to be separated and identified. Fractional distillation separates components based on their boiling points, which is not useful in this case since the dyes have the same boiling point. Coagulation involves the clumping of particles in a liquid, which is not applicable in this scenario. Recrystallization is used to purify solids and is not applicable for isolating dyes from a liquid mixture.

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Basic Biochemistry And Synthetic Polymers

Energy And Energy Changes

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Question 41 Report

Which of the following compounds is a soapless detergent?

C ₁₂H ₂₅OSO₃Na Correct answer

C ₁₇H ₃₅COONa

C ₆H₅OH₃

C ₄H₉COOC₂H ₅

Answer Details

The compound that is a soapless detergent is C ₁₂H ₂₅OSO₃Na. Soapless detergents are also known as synthetic detergents, and they are produced from organic compounds. They do not contain any soap, hence the name soapless. They are usually made by combining an alkyl benzene or a long-chain alcohol with a sulfonic acid or a sulfuric acid, which creates a compound that is highly effective at removing dirt and grease from surfaces. This compound is a sodium alkyl benzene sulfonate, which is a type of synthetic detergent commonly used in household cleaning products.

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Acids, Bases And Salts

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Question 42 Report

The reaction that takes place at the cathode when an aqueous solution of NaCI is electrolysed using carbon electrodes is

2H⁺_2(g) + 2e^- → H_2(g) Correct answer

Na⁺_2(g) + e^- → Na_(s)

4OH^- → 2H₂O_(l) + O_2(g) +4e_-

2CI_- → CI_2(g) + 2e^-

Answer Details

The reaction that takes place at the cathode when an aqueous solution of NaCl is electrolyzed using carbon electrodes is: - 2H⁺_2(g) + 2e^- → H_2(g) During the electrolysis of an aqueous solution of NaCl using carbon electrodes, the NaCl molecules dissociate into Na⁺ and Cl^- ions. The Na⁺ ions are attracted towards the cathode where they gain electrons and become sodium atoms which are deposited on the cathode. However, water molecules are also present in the solution and can be reduced instead of Na⁺ ions. The reduction of water molecules results in the production of hydrogen gas. The hydrogen gas bubbles out of the solution, and the overall reaction at the cathode can be represented as: 2H⁺_(aq) + 2e^- → H_2(g) Therefore, option A is the correct answer.

Read lesson note on Electrolysis (JAMB)

Electrolysis

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