JAMB UTME - Chemistry - 1994

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Question 2 Report

In the diagram above, R is a mixture of

potassium tetraxochlorate (VII) and concentrated H2SO4

potassium trioxochlorate (V) and concentrated H2SO4

potassium tetratoxomanganate (VII) and concentrated HCI

manganes (IV) oxide and concentrated HCI Correct answer

Answer Details

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

Acids, Bases And Salts

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Question 3 Report

Which of the following is the correct order of decreasing activity of the metals Fe, Ca, Al and Na?

Fe> Ca> Al> Na

Na> Ca> Al> Fe Correct answer

Al> Fe> Na> Ca

Ca> Na> Fe>, Al

Answer Details

The reactivity of metals is related to their tendency to lose electrons and form positive ions. Metals that lose electrons easily are more reactive, while metals that don't lose electrons easily are less reactive. The order of decreasing activity of the metals Fe, Ca, Al, and Na can be determined by their position in the reactivity series. In the reactivity series, metals are listed in order of decreasing reactivity. The most reactive metals are at the top, and the least reactive metals are at the bottom. The reactivity series is based on how readily the metals react with water and dilute acids. The correct order of decreasing activity of the metals Fe, Ca, Al, and Na is: Na > Ca > Al > Fe This is because Na is the most reactive metal, followed by Ca, Al, and Fe. Therefore, is the correct answer. Na (s) + H2O (l) -> NaOH (aq) + 1/2H2 (g) Ca (s) + H2O (l) -> Ca(OH)2 (aq) + H2 (g) Al (s) + 3H2O (l) -> Al(OH)3 (aq) + 3/2H2 (g) Fe (s) + H2O (l) -> Fe(OH)2 (s) + H2 (g)

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Metals And Their Compounds

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Question 4 Report

The solubility, in moles per dm3 of 20.2 g of potassium trioxonitrate (V) dissolve in 100 g of the resulting mixture is?(K = 39, O = 16, N =14).

0.10

0.20

1.00

2.00 Correct answer

Answer Details

The first step to solve the problem is to calculate the molar mass of potassium trioxonitrate (V), which is given by: KNO₃ = (1 x 39) + (1 x 14) + (3 x 16) = 101 g/mol Next, we need to calculate the number of moles of potassium trioxonitrate (V) that are present in 20.2 g: moles of KNO₃ = mass / molar mass = 20.2 / 101 = 0.2 mol Now, we need to calculate the total mass of the resulting mixture. This is given by: mass of resulting mixture = mass of KNO₃ + mass of water = 20.2 + 100 = 120.2 g Finally, we can calculate the solubility of potassium trioxonitrate (V) in moles per dm³ by dividing the number of moles of KNO₃ by the volume of the resulting mixture in dm³. The volume of the resulting mixture is equal to 0.1 dm³ (since 100 g of water is equal to 0.1 dm³): solubility = moles / volume = 0.2 / 0.1 = 2.0 Therefore, the solubility of potassium trioxonitrate (V) in moles per dm³ is 2.0 mol/dm³, which corresponds to option (D).

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Oxidation And Reduction

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Question 5 Report

20 cm3 of a 2.0 M solution of ethanoic acid was added to excess of 0.05 M sodium hydroxide. The mass of the salt produced is?(Na = 23, C = 12, O = 16, H = 1)

2.50 g

2.73 g

3.28 g Correct answer

4.54 g

Answer Details

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Stoichiometry And Chemical Reactions

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Question 6 Report

Which of the following is TRUE of Le Chatelier's Principle for an exothermic reaction?

Increase in temperature will cause an increase in the equilibrium constant

Increase in temperature will cause a decrease in the equilibrium constant Correct answer

Addition of a catalyst will cause an increase in the equilibrium constant

Addition of a catalyst will cause a decrease in the equilibrium constant

Answer Details

Le Chatelier's Principle states that if a system at equilibrium is subjected to a change in temperature, pressure, or concentration of reactants or products, then the equilibrium shifts in the direction that tends to undo the effect of the change. For an exothermic reaction, increasing the temperature will cause a shift in the equilibrium towards the reactants, in order to reduce the effect of the added heat. This means that the equilibrium constant will decrease since it is a ratio of the concentrations of products to reactants at equilibrium. Therefore, the correct answer is "Increase in temperature will cause a decrease in the equilibrium constant." The addition of a catalyst will not affect the position of the equilibrium, but it will increase the rate at which the reaction reaches equilibrium. Therefore, the statement "Addition of a catalyst will cause an increase in the equilibrium constant" is false.

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

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Question 7 Report

MnO4(aq) + 8H + (aq) + 5Fe2+ → Mn2+(aq) + 4H2O(I). The oxidation number of manganese in the above reaction changed from?

+7 to +2 Correct answer

+6 to +2

+5 to +2

+4 to +2

Answer Details

In the given chemical reaction, MnO₄^- ion is reduced to Mn²⁺ ion, indicating a decrease in the oxidation number of manganese. To determine the change in oxidation number, we need to know the oxidation state of manganese in the reactant and product side. In MnO₄^-, oxygen has an oxidation state of -2, so the oxidation state of Mn can be calculated as follows: (+4) + 4(-2) = -8 x + (-8) = -1 (the net charge of MnO₄^-) Solving for x, the oxidation state of Mn in MnO₄^- is +7. On the product side, there are two H₂O molecules, so the oxidation state of Mn can be calculated as follows: x + 4(+2) + 2(-2) = 0 (the net charge of Mn2+) Solving for x, the oxidation state of Mn in Mn²⁺ is +2. Therefore, the oxidation state of Mn changes from +7 to +2 in the given reaction, which means that the correct answer is "+7 to +2".

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Oxidation And Reduction

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Question 8 Report

In an electrolytic set-up to protect iron from corrosion, the iron is?

made cathode

made anode

used with a metal of lower electropositive potential

initially coated with tin Correct answer

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Electrolysis

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Question 9 Report

The ∆H for the reaction represented by the energy profile above is

-100 kJ mol--1

+ 100 kJ mol-1

+50 kJ mol-1

-50 kJ mol-1 Correct answer

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Energy Changes

Energy And Energy Changes

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Question 10 Report

To what temperature must a gas 273 K be heated in order to double both its volume and pressure?

298 K

546 K

819 K

1092 K Correct answer

Answer Details

According to the Ideal Gas Law, PV = nRT, where P is the pressure, V is the volume, n is the number of moles of gas, R is the gas constant, and T is the temperature in Kelvin. If we want to double both the volume and pressure of the gas while keeping the number of moles constant, then we can use the combined gas law, which states: (P1V1)/T1 = (P2V2)/T2 where P1 and V1 are the initial pressure and volume, and P2 and V2 are the final pressure and volume. Since we want to double both the pressure and volume, we can set: P2 = 2P1 V2 = 2V1 Substituting these values into the combined gas law, we get: (P1*2V1)/T1 = (2P1*2V1)/T2 Simplifying, we get: T2 = T1*4 So, the temperature must be quadrupled in order to double both the pressure and volume. Since the initial temperature is 273 K, we can multiply it by 4 to get the final temperature: T2 = 273 K * 4 = 1092 K Therefore, the answer is 1092 K.

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

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Question 11 Report

2HCL(ag) + CaCO3(ag) ? CaCL2(ag) + H2O(1) + CO

From the reaction above, which of the following curves represents the consumption of calcium trioxocarbonate (IV) as dilute HCL is added to it?

M Correct answer

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Question 12 Report

Which of these metals CANNOT replace hydrogen from alkaline solutions?

Alulinium

Zinc

Tin

Iron Correct answer

Answer Details

Read lesson note on Metals And Their Compounds (JAMB)

Metals And Their Compounds

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Question 13 Report

What volume of oxygen measured at s.t.p would be liberated on electrolysis by 9650 coulombs of electricity?

(Molar volume of gas = 22.4 dm3, F = 96,500 C mol-)

22.4 dm3

11.2 dm3

1.12 dm3

0.560 dm3 Correct answer

Answer Details

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Electrolysis

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Question 14 Report

Which of the following is NOT true of metals?

They are good conductors of electricity

They ionize by electron loss

Their oxides are acidic Correct answer

They have high melting points

Answer Details

The statement that is NOT true of metals is: "Their oxides are acidic". Metals are elements that tend to have certain characteristics such as good conductivity of heat and electricity, high melting points, and the ability to lose electrons to form positively charged ions or cations. When a metal reacts with oxygen, it forms metal oxide, which may be either basic or amphoteric, but not acidic. Basic oxides react with acids to form salts and water, while amphoteric oxides can react as either an acid or a base. Therefore, their oxides are not acidic, but either basic or amphoteric in nature.

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Metals And Their Compounds

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Question 15 Report

Which of the following compounds is a base?

CO2

CaO Correct answer

H3PO3

CH3COOCH3

Answer Details

A base is a substance that can accept hydrogen ions (H+) or donate hydroxide ions (OH-) in a chemical reaction. Among the given options, CaO is a base. When CaO dissolves in water, it reacts with water to form Ca(OH)2, a strong base that dissociates into calcium ions (Ca2+) and hydroxide ions (OH-) in solution. Therefore, CaO is a base.

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Acids, Bases And Salts

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Question 16 Report

Element X, Y and Z belong to a groups I, V and VII respectively. Which of the following is TRUE about the bond types of XZ and YZ3?

Both are electrovalent

Both are covalent

XZ is electrovalent and YZ3 is covalent Correct answer

XZ is covalent and YZ3 is electrovalent

Answer Details

The bond types of XZ and YZ can be determined based on the electronic configuration of the elements. Group I elements, such as X, have one valence electron, while Group V elements, such as Y, have five valence electrons. Group VII elements, such as Z, have seven valence electrons. To achieve stability, Group I elements tend to lose one electron to achieve a stable noble gas configuration, while Group V elements tend to gain three electrons to achieve a stable noble gas configuration. Group VII elements tend to gain one electron to achieve a stable noble gas configuration. Therefore, in the case of XZ, element X will lose one electron to element Z to form an electrovalent or ionic bond. In the case of YZ, element Y will share three electrons with element Z to form a covalent bond. Thus, the correct option is: XZ is electrovalent and YZ is covalent.

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Chemical Bonds (Ghana Only)

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Question 17 Report

Sodium chloride has no solubility product value because of its?

saline nature

high solubility Correct answer

low solubility

insolubility

Answer Details

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

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Question 18 Report

Which of these solutions will give a white precipitate with a solution of barium chloride acidified with hydrochloric acid?

Sodium trioxocarbonate (IV) Correct answer

Sodium tetraoxosulphate (IV)

Sodium trioxosulphate (IV)

Sodium sulphide

Answer Details

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

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Question 19 Report

A major effect of oil pollution in coastal waters is the?

destruction of marine life

desalination of the water

increase in the acidity of the water Correct answer

detoxification of the water

Answer Details

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Environmental Pollution

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Question 20 Report

A few drops of concentrated PCI are added to about 10cm3 of a solution of pH 3.4. The pH of the resulting mixtures is?

less than 3.4

greater than 3.4

unaltered Correct answer

the same as that of pure water

Answer Details

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

Acids, Bases And Salts

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Question 21 Report

A mixture of sand, ammonium chloride and sodium chloride is best separated by?

sublimation followed by addition of water and filteration Correct answer

sublimation followed by addition of water and evaporation

addition of water followed by filtration and sublimation

addition of water followed by crystallization and sublimation

Answer Details

The best method to separate the mixture of sand, ammonium chloride, and sodium chloride is "sublimation followed by addition of water and filtration". The mixture contains two sublimating components, sand and ammonium chloride, and one non-sublimating component, sodium chloride. Therefore, sublimation can be used to separate the mixture into two components. By heating the mixture, ammonium chloride sublimes, and can be collected on a cool surface as solid. The remaining mixture will contain sand and sodium chloride. Next, water can be added to dissolve the sodium chloride, leaving the sand as a residue. The solution containing sodium chloride can then be filtered to remove any insoluble impurities, leaving behind a clear solution of sodium chloride. Therefore, the correct option for separating the given mixture is "sublimation followed by addition of water and filtration".

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 22 Report

One mole of a hydrocarbon contains 48 g of carbon. If it vapour density is 28, the hydrocarbon is?

an alkane

an alkene Correct answer

an alkyne

aromatic (C = 12, H = 1)

Answer Details

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

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Question 23 Report

The number of electrons in the valence shell of an element of atomic number 14 is?

4 Correct answer

Answer Details

The atomic number of an element tells us the number of protons in its nucleus, which is also equal to the number of electrons in the neutral atom. The element with atomic number 14 is Silicon (Si). To determine the number of electrons in the valence shell, we need to look at the electron configuration of Silicon. The electron configuration of Silicon is 1s2 2s2 2p6 3s2 3p2. The valence shell of an atom is the outermost shell containing electrons, and in the case of Silicon, this is the 3rd shell (3s2 3p2). The number of electrons in the valence shell of Silicon is equal to the sum of the electrons in the s and p orbitals of that shell, which is 2 + 2 = 4. Therefore, the correct answer is 4, which means that Silicon has 4 valence electrons.

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Question 24 Report

When sodium is added to ethanol, the products are?

sodium hydroxide and water

sodium hydroxide and hydrogen

sodium ethoxide and water

sodium ethoxide and hydrogen Correct answer

Answer Details

When sodium is added to ethanol, the products are sodium ethoxide (NaC2H5O) and hydrogen gas (H2). This is because sodium is a highly reactive metal that reacts with ethanol to displace the hydrogen atom attached to the carbon atom in the -OH group. As a result, the hydrogen atom combines with another hydrogen atom to form hydrogen gas, while the remaining ethoxide ion combines with the sodium cation to form sodium ethoxide. Therefore, the correct option is: sodium ethoxide and hydrogen gas.

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Electrolysis

Acids, Bases And Salts

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Question 25 Report

For a gas, the relative molecular mass is equal to 2Y. What is Y?

The mas of the gas

The vapour density of the gas Correct answer

The volume of the gas

The temperature of the gas

Answer Details

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

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Question 26 Report

H- + H2(I)O → H2(g) + OH-(aq). From the equation above, it can be inferred that the?

reaction is a double decomposition

hydride ion is a reducing agent Correct answer

hydride ion is an oxidizing agent

reaction is neutralization

Answer Details

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Oxidation And Reduction

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Question 27 Report

The shape of ammonia molecule is?

trigonal planar Correct answer

octahedral

square planar

tetrahedral

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Read lesson note on Atomic Structure And Bonding (JAMB)

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Question 28 Report

\( \mathrm{MnO_4(aq) + 8H + 5Fe^{2+} \rightarrow Mn^{2+}(aq) + 5Fe^{3+}(aq) + H_2O} \). The oxidation number of maganese in the above reaction changed from

+8 to +2 Correct answer

+6 to +2

+5 to +2

+4 to +2

Answer Details

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

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 29 Report

When sodium ethanoate is treated with a few drops of concentrated tetraoxosulphate(vi)acid. one of the products is

CH3COOH Correct answer

CH3COOCH3

CH3COOC2H5

C2H5COOCH3

Answer Details

When sodium ethanoate (also known as sodium acetate) is treated with concentrated tetraoxosulphate (VI) acid (also known as sulfuric acid), one of the products formed is ethanoic acid (CH3COOH). This is due to the fact that the sulfuric acid protonates the acetate ion in the sodium ethanoate solution, leading to the formation of ethanoic acid and sodium sulfate as the other product. Therefore, the correct option is: CH3COOH.

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Question 30 Report

At the same temperature and pressure, 50 cm3 of nitrogen gas contains the same number of molecules as?

25 cm3 of methane

40 cm3 of hydrogen

50 cm3 of ammonia Correct answer

100 cm3 of chlorine

Answer Details

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

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Question 31 Report

The IUPAC name of the compound above is

2,2-dimethyl but -1-yne

2,2-dmethyl but -1-ene

3,3-dimethyl but -1-ene Correct answer

3,3-dimethyl but-1-yne

Answer Details

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Question 32 Report

Which of the following physical properties decreases down a group in the periodic table?

Atomic radius

Ionic radius Correct answer

Electropositivity

Electronegativity

Answer Details

Read lesson note on Atomic Structure And Bonding (JAMB)

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Question 33 Report

An anhydride is an oxide of non-mental?

which will not dissolve in water

whose solution in water has a pH greater than 7

whose solution in water has a pH less than 7 Correct answer

whose solution in water has a pH of 7

Answer Details

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

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Question 34 Report

A solid that absorbs water from he atmosphere and forms an aqueous solution is?

hydrophilic

efforescent

deliquescent Correct answer

hygroscopic

Answer Details

Read lesson note on Solubility (JAMB)

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

Solubility

Solubility Of Substances (Ghana Only)

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Question 35 Report

In the diagram above the activation energy is represented by

y - x Correct answer

x - z

Answer Details

In the diagram, the activation energy is represented by the vertical distance between the reactants (energy level x) and the maximum point in the curve (energy level y). Therefore, the answer is "y - x".

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

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Question 36 Report

Use the diagram above to answer this question.

The reaction taking place in the flask above is known as

hydrolysis

double decomposition

dehydration Correct answer

pyrolysis

Answer Details

The reaction taking place in the flask above is dehydration. Dehydration is a chemical reaction that involves the removal of water from a molecule or compound. In the diagram, there is a reactant (the pink molecule) that loses a water molecule (H2O) and forms a new compound (the blue molecule). This process is known as dehydration, and it is represented by the removal of water (H2O) from the pink molecule, leaving behind a double bond (represented by the black line) between the two carbon atoms.

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Acids, Bases And Salts

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Question 37 Report

The general formula of alkanoates is?

RCHO

R2CO Correct answer

RCOOH

RCOOR

Answer Details

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

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

Chemistry Of Carbon Compounds (Ghana Only)

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Question 38 Report

The set-up above would be useful for determining the amount of

oxygen in air

water vapour in air Correct answer

CO2 in air

arygen in air

Answer Details

Read lesson note on Air (JAMB)

Air

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Question 39 Report

The densities of two gases, X and Y, are 0.5 g dm-3 and 2.0 dm-3 respectively.

What is the rate of diffusion of X relative to Y?

0.1

0.5

2.0 Correct answer

4.0

Answer Details

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

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Question 40 Report

Clothes should be properly rinsed with water after bleaching because?

the bleach decolourizes the cothes

chlorine reacts with fabrics during bleaching

the clothes are sterilized during bleaching

hydrogen chloride solution is produced during bleaching Correct answer

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Oxidation And Reduction

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Question 41 Report

The diagram above represents an atom of

magnesium Correct answer

helium

chlorine

neon

Answer Details

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

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Structure Of The Atom (Ghana Only)

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Question 42 Report

Which of the following reagents will confirm the presence of unsaturation in a compound?

Fehling's solution

Bromine water Correct answer

Tollen's reagent

Benedict's solution

Answer Details

Bromine water can confirm the presence of unsaturation in a compound. Unsaturated compounds contain multiple bonds between carbon atoms, and these double or triple bonds can readily react with bromine water (an aqueous solution of bromine) by breaking the double or triple bond and forming a colorless dibromo compound. As a result, if the compound has unsaturation, bromine water will lose its characteristic orange color upon reaction with the compound, indicating the presence of unsaturation. The other reagents listed are used for different types of chemical tests, such as reducing sugars (Fehling's and Benedict's solutions) or identifying aldehydes or ketones (Tollen's reagent).

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Question 43 Report

Crude copper could be purified by the electrolysis of concentrated copper (II) chloride if the crude copper is?

made both the anode and the cathode

made the cathode

made the anode Correct answer

dissolved in the solution

Answer Details

Read lesson note on Electrolysis (JAMB)

Electrolysis

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Question 44 Report

Which of the following compounds is NOT an isomers of 2,2 dimethylbutane?

2-methylbutane Correct answer

3-methylpentane

2,3-dimethylbutane

2-methylpentane

Answer Details

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

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Question 45 Report

An increase in temperature causes an increase in the pressure of a gas because?

it decreases the number of collision between the molecules

the molecules of the gas bombard the walls of the container more frequently

it increases the number of collision between the molecules Correct answer

it causes the molecules to combine

Answer Details

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