Which of the following statement is TRUE of the complete hydrolysis of a glyceride by sodium hydroxide?

3 moles of NaOH are required for each mole of glyceride

3 moles of glycerol are produced

only one mole of soap is formed

concentrated H2SO4 is essential for the completion of the reaction.

Which of the following does NOT contain aluminum as a component?

Container for trioxonitrate (v) acid

The function of sulphur during the vulcanization of rubber is to

form chains which bind rubber molecules together

act as a catalyst for the polymerization of rubber molecules

convert rubber from thermosetting to thermoplastic polymer

form chains which bind rubber molecules together

break down rubber polymer molecules

Which of the following increases as boiling water changes to steam?

degree of disorder of the system

Which of the following roles does sodium chloride play in preparation? It

purifies the soap, accelerates the decomposition of fat and oil

converts the fat acid to its sodium salt

JAMB UTME - Chemistry - 2022 | Green Bridge CBT

Question 1 Report

A piece of radioactive element has initially 8.0×10^22 atoms. The half life of two days after 16 days the number of atom is

5×10^21

5×10^22

25×10^21

25×10^22

Kinetic Theory Of Matter And Gas Laws

View Answer

Question 2 Report

2-methylprop-1-ene is a structural isomer of?

But-1-yne

2-methyl But-1-ene

3-methyl prop-1-yne

But-2-ene

Chemistry Of Carbon Compounds (Nigeria Only)

View Answer

Question 3 Report

\(\mathrm{N_2O_4}\) ? \(2\mathrm{NO_2}\) (? = -ve)

From the reaction above, which of these conditions would produce the highest equilibrium yield for \(\mathrm{N_2O_4}\)?

Low temperature and high pressure

Low temperature and low pressure

high temperature and low pressure

high temperature and high pressure

Answer Details

The highest equilibrium yield of N2O4 would be produced at low temperature and low pressure. In a chemical reaction, the position of the equilibrium can be influenced by changing the temperature or pressure. A decrease in temperature or an increase in pressure favors the side of the reaction with the fewer moles of gas (in this case, N2O4). This means that, if the temperature is low and the pressure is low, there will be more N2O4 at equilibrium, as the reaction will shift to the right to counteract the reduction in the concentration of N2O4. So, low temperature and low pressure would produce the highest equilibrium yield of N2O4.

Read lesson note on Chemical Combination (JAMB)

Chemical Combination

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Question 4 Report

Which of the following is used as a moderator to control nuclear fission?

Lead

Heavy water

Iron

Chromium

Answer Details

Heavy water (D2O) is used as a moderator to control nuclear fission. A moderator is a substance that is used to slow down the neutrons produced in a nuclear reaction, making them more likely to be captured by the fuel nuclei and causing further fission. Heavy water is a type of water that contains a larger amount of the isotope deuterium (D) than regular water. Deuterium has an extra neutron compared to the more common hydrogen isotope, and this makes heavy water more effective at slowing down neutrons than regular water. Lead, iron, and chromium are not typically used as moderators in nuclear reactors. Lead can be used as a shield to absorb radiation, while iron and chromium are used in the construction of the reactor vessel and other components.

Read lesson note on Electrolysis (JAMB)

Electrolysis

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Question 5 Report

Which of the following best represent solid gas mixture?

milk

kerosene

soil

smoke

Kinetic Theory Of Matter And Gas Laws

States Of Matter

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Question 6 Report

6g of Mg was to 100cm3 of 1 moldm3 H2 SO4 . What mass of Mg remained undissolved? (Mg = 24)

0.24g

2.4g

3.6g

0.36g

Answer Details

The balanced chemical equation for the reaction between magnesium (Mg) and sulfuric acid (H2SO4) is: Mg + H2SO4 -> MgSO4 + H2 According to the equation, one mole of Mg reacts with one mole of H2SO4 to produce one mole of magnesium sulfate (MgSO4) and one mole of hydrogen gas (H2). Since the concentration of the sulfuric acid is 1 moldm3, this means that there is one mole of H2SO4 in every 1 liter (1000 cm3) of solution. To determine the amount of Mg that reacts with the H2SO4, we need to use stoichiometry. One mole of Mg reacts with one mole of H2SO4, so the amount of Mg that reacts with 1 moldm3 of H2SO4 is given by: 6g / 24g/mol = 0.25 mol Since the reaction is 1:1, this means that 0.25 mol of H2SO4 is consumed in the reaction. The volume of the solution is 100cm3 (0.1 dm3), so the amount of H2SO4 in the solution is: 1 mol/dm3 x 0.1 dm3 = 0.1 mol The amount of H2SO4 that remains after the reaction is: 0.1 mol - 0.25 mol = -0.15 mol This negative value means that all of the H2SO4 was consumed in the reaction, and there is excess Mg left over. The mass of Mg that remains undissolved is given by: 0.15 mol x 24g/mol = 3.6g Therefore, the correct answer is 3.6g.

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

Kinetic Theory Of Matter And Gas Laws

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Question 7 Report

30 cm3 of oxygen at 10 atmosphere pressure is placed in a 20 dm3 container. Calculate the new pressure if the temperature is kept constant.

6.7 atm

15.0 atm

6.0 atm

66.0 atm

Answer Details

Given:

Initial pressure, 𝑃1=10P1=10 atmospheres

Initial volume, 𝑉1=30 cm3V1=30cm3

Final volume, 𝑉2=20 dm3V2=20dm3

First, convert all volumes to the same units. Since 1 dm3dm3 is 1000 cm3cm3:

𝑉2=20 dm3=20×1000 cm3=20000 cm3V2=20dm3=20×1000cm3=20000cm3

Now, using Boyle's Law:

𝑃1𝑉1=𝑃2𝑉2P1V1=P2V2

Substitute the known values into the equation:

10×30=𝑃2×2000010×30=P2×20000

300=𝑃2×20000300=P2×20000

Solve for 𝑃2P2:

𝑃2=30020000P2=20000300

𝑃2=0.015 atmospheresP2=0.015atmospheres

Therefore, the new pressure if the temperature is kept constant is:

0.015 atmospheres0.015atmospheres

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

Kinetic Theory Of Matter And Gas Laws

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Question 8 Report

An organic compound which liberate carbon(iv)oxide from trioxocarbonate(iv) solution is likely to be?

C

_{2}

H

_{5}

OH

C

_{3}

H

_{4}

C

_{6}

H

_{6}

CH

_{3}

COOH

Answer Details

The organic compound that liberates carbon(iv)oxide from trioxocarbonate(iv) solution is CH3COOH (acetic acid). When acetic acid is added to a solution of trioxocarbonate(iv) (carbonate) it reacts to form carbon(iv)oxide gas, water and a salt. The balanced chemical equation for the reaction is: 2CH3COOH + Na2CO3 → CO2 + 2H2O + 2NaCH3COO The carbon(iv)oxide gas is released as bubbles, causing the solution to fizz. Therefore, CH3COOH is the organic compound that liberates carbon(iv)oxide from trioxocarbonate(iv) solution.

View Answer

Question 9 Report

In which of the following will hydrogen form ionic compound?

HCL

NaH

NH

_{3}

CH

_{4}

Chemical Combination

Organic Compounds

View Answer

Question 10 Report

If the volume of a given mass of a gas at 0ºc is \(29.5\text{cm}^3\). What will be the volume of the gas at 15ºc, given that the pressure remains constant.

31.6

62.2

32.7

31.1

Kinetic Theory Of Matter And Gas Laws

View Answer

Question 11 Report

Addition of charcoal to the filter bed of sand during water treatment for township supply is to?

prevent goiter

prevent tooth decay

remove odour

kill germs

Answer Details

The addition of charcoal to the filter bed of sand during water treatment for township supply is to remove odors and improve the taste of the water. Charcoal is a porous material that can adsorb impurities and chemicals from the water, such as dissolved organic matter that can contribute to unpleasant tastes and odors. This process helps to produce a better-quality drinking water that is free from unpleasant tastes and odors. It should be noted that while the addition of charcoal can help remove impurities, it does not kill germs or prevent tooth decay or goiter. Other water treatment methods, such as disinfection with chlorine or ultraviolet light, are required to kill harmful microorganisms and ensure the safety of the drinking water.

Read lesson note on Solubility (JAMB)

Solubility

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Question 12 Report

A metal which can be used as sacrificial anode for preventing corrosion of length of iron pipe is

copper

magnesium

silver

lead

Metals And Their Compounds

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Question 13 Report

GAS	\( \mathrm{CO_2} \)	\( \mathrm{N_2} \)	\( \mathrm{O_2} \)
% BY VOLUME	4	72	24

The above table shows the compositions of the atmosphere of planet X. Which of these gases are present in higher percentages on earth?

CO

_{2}

and O

_{2}

N

_{2}

and CO

_{2}

CO

_{2}

, O

_{2}

and N

_{2}

O

_{2}

and N

_{2}

Separation Of Mixtures And Purification Of Chemical Substances

View Answer

Question 14 Report

H2SO4 is used to remove rust on the surface of iron (picking) before electroplating. The type of reaction involved is

redox reaction

Neutralization

Double decomposition

Hydrolysis

Answer Details

The type of reaction involved when using H2SO4 to remove rust on the surface of iron is a redox reaction. This is because the sulfuric acid oxidizes the iron in the rust, converting it into iron(II) sulfate, while the acid itself is reduced to sulfur dioxide. The overall reaction can be written as follows: Fe2O3(s) + 3H2SO4(aq) → Fe2(SO4)3(aq) + 3H2O(l) In this reaction, the iron in Fe2O3 is oxidized from a +3 to a +2 oxidation state, while the sulfur in H2SO4 is reduced from a +6 to a +4 oxidation state. This transfer of electrons between the reactants is what defines a redox reaction.

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

Read lesson note on Redox Reactions (WAEC)

Kinetic Theory Of Matter And Gas Laws

Redox Reactions

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Question 15 Report

The following non-metal form acidic oxides with oxygen except?

phosphorus

sulphur

carbon

chlorine

Answer Details

An acidic oxide is an oxide that reacts with water to form an acidic solution. Non-metals have a greater tendency to form acidic oxides than metals. Therefore, among the given options, the non-metal that does not form an acidic oxide with oxygen would be the one that does not react with water to form an acidic solution. Out of the given options, chlorine is the non-metal that does not form acidic oxides with oxygen. Chlorine reacts with oxygen to form a number of oxides such as chlorine monoxide (Cl2O), chlorine dioxide (ClO2), and chlorine trioxide (ClO3), but none of these oxides react with water to form an acidic solution. Instead, they react with water to form oxyacids or oxoacids such as hypochlorous acid (HClO), chlorous acid (HClO2), and chloric acid (HClO3), which are stronger acids than the oxides. Therefore, the correct answer is chlorine.

Read lesson note on Organic Compounds (JAMB)

Read lesson note on Non-metals And Their Compounds (JAMB)

Organic Compounds

Non-metals And Their Compounds

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Question 16 Report

A sample of gas with an initial volume of 2.5 dm3 is heated and then allowed to expand to 7.5 dm3 at constant at pressure. What is the ratio of the final temperature of the initial absolute temperature?

3:1

1:3

2:5

5:2

Answer Details

According to Charles's Law, the ratio of the initial and final temperatures is equal to the ratio of the initial and final volumes at constant pressure. The ratio of the final volume to the initial volume is: Vf / Vi = 7.5 dm3 / 2.5 dm3 = 3 Therefore, the ratio of the final temperature to the initial temperature is also 3: Tf / Ti = Vf / Vi = 3 So the answer is 3:1.

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

Kinetic Theory Of Matter And Gas Laws

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Question 17 Report

Which of the following will act as both oxidizing agents and reducing agents?

H2 S

NH3

Cl2

SO2

Answer Details

The oxidizing and reducing properties of a substance depend on its ability to gain or lose electrons. A substance that can gain electrons acts as an oxidizing agent, while a substance that can lose electrons acts as a reducing agent. Among the given options, both Cl2 (chlorine gas) and SO2 (sulfur dioxide) can act as both oxidizing and reducing agents depending on the reaction conditions. - Cl2 can act as an oxidizing agent when it gains electrons to form Cl- ions, and it can act as a reducing agent when it loses electrons to form Cl+ ions. For example, in the reaction Cl2 + 2KBr → 2KCl + Br2, chlorine gas is acting as an oxidizing agent since it is gaining electrons from bromide ions to form bromine gas. However, in the reaction 2Cl- + Cl2 → 2Cl2-, chlorine gas is acting as a reducing agent since it is losing electrons to form chloride ions. - SO2 can act as an oxidizing agent when it gains electrons to form sulfite ions (SO32-), and it can act as a reducing agent when it loses electrons to form sulfur trioxide (SO3). For example, in the reaction SO2 + 2H2S → 3S + 2H2O, sulfur dioxide is acting as a reducing agent since it is losing electrons to form elemental sulfur. However, in the reaction 2SO32- + O2 → 2SO42-, sulfur dioxide is acting as an oxidizing agent since it is gaining electrons to form sulfate ions. H2S (hydrogen sulfide) and NH3 (ammonia) are not likely to act as both oxidizing and reducing agents under normal conditions. H2S tends to act as a reducing agent by donating electrons to oxidizing agents, while NH3 tends to act as a reducing agent by donating electrons to oxidizing agents or as a base by accepting protons.

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

Chemical Bonds (Ghana Only)

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Question 18 Report

Complete dehydrogenation of ethyne yields

benzene

methane

ethane

propane

Chemistry Of Carbon Compounds (Nigeria Only)

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Question 19 Report

What is the shape of a molecule of CCl4?

Pyramid

tetrahedral

Trigonal planar

linear

Answer Details

The shape of a molecule of CCl4 is tetrahedral.

Read lesson note on Atomic Structure And Bonding (JAMB)

Atomic Structure And Bonding

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Question 20 Report

A certain volume of gas at 298k is heated such that its volume and pressure are now four times the original values. What is the new temperature?

18.6K

100.0K

298.0K

4768.0K

Answer Details

We can use the ideal gas law to solve this problem, which states that PV = nRT, where P is pressure, V is volume, n is the number of moles of gas, R is the gas constant, and T is temperature in kelvin. If the volume and pressure are both increased by a factor of 4, then the new volume V' and new pressure P' are given by: V' = 4V P' = 4P Substituting these values into the ideal gas law, we get: (4P)(4V) = nR(T') Simplifying this equation, we get: 16PV = nRT' Dividing both sides by PV, we get: 16 = nRT' / PV Since n, R, and P are constant, we can simplify this to: 16 = T' / T Solving for T', we get: T' = 16T Therefore, the new temperature is 16 times the original temperature. Substituting T = 298 K, we get: T' = 16 x 298 K = 4768 K So the correct answer is 4768.0K.

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

Kinetic Theory Of Matter And Gas Laws

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Question 21 Report

An organic compound with fishy smell is likely to have a general formula?

RCONHR

^{1}

RCONH

_{2}

RNH

_{2}

RCOR

^{1}

Answer Details

The organic compound with a fishy smell is most likely to have the general formula RNH2, which represents a primary amine. Amines are organic compounds that contain a nitrogen atom bonded to one or more carbon atoms. Primary amines have one alkyl or aryl group and two hydrogen atoms bonded to the nitrogen atom. Some primary amines have a fishy smell, which is caused by the presence of volatile amines. These amines are small molecules that can easily evaporate and have a strong odor, similar to that of fish. Examples of compounds that have a fishy smell include trimethylamine, which is found in fish, and butylamine, which is used in the production of rubber and pharmaceuticals. In summary, the organic compound with a fishy smell is likely to have the general formula RNH2, which represents a primary amine.

View Answer

Question 22 Report

Copper (II) tetraoxosulphate (IV) is widely used as

fertilizer

fungicide

Disinfectant

purifier

Answer Details

Copper (II) tetraoxosulphate (IV), also known as copper sulfate or CuSO4, is widely used as a fungicide and a disinfectant. As a fungicide, copper sulfate is effective in controlling fungal diseases in plants, including mildew, leaf spots, and blights. It is also used as a fungicide in swimming pools to prevent the growth of algae. As a disinfectant, copper sulfate is effective in killing bacteria and viruses. It is used in a variety of applications, including in the production of animal feed, as a preservative for wood, and in water treatment to kill bacteria and algae. While copper sulfate has been used as a fertilizer in the past, its use in this capacity has largely been replaced by other compounds. It is not commonly used as a purifier.

Read lesson note on Stoichiometry And Chemical Reactions (WAEC)

Read lesson note on Environmental Pollution (JAMB)

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

Stoichiometry And Chemical Reactions

Environmental Pollution

Periodic Chemistry (Ghana Only)

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Question 23 Report

Electrons enter into orbitals in order of increasing energy as exemplified by?

1S

^{2}

2S

^{2}

2PX

^{2}

2py

^{2}

2pz

^{0}

3s

^{0}

1S

^{2}

2S

^{2}

2PX

^{2}

2py

^{1}

2pz

^{1}

3s

^{0}

1S

^{2}

2S

^{2}

2PX

^{1}

2py

^{1}

2pz

^{1}

3s

^{1}

1S

^{2}

2S

^{2}

2PX

^{2}

2py

^{2}

2pz

^{0}

3s

^{1}

Atomic Structure And Bonding

View Answer

Question 24 Report

The boiling point of water, ethanol, toulene and butan-2-ol are 373.0k, 351.3k, 383.6k and 372.5k respectively, which liquid has the highest vapour pressure at 323.0k

water

toluene

ethanol

butan-2-ol

Kinetic Theory Of Matter And Gas Laws

View Answer

Question 25 Report

Mixing aqueos solution of barium hydroxide and sodium tetraoxocarbonate (iv) yields a white precipitate of

Barium oxide

Sodium tetraoxocarbonate

Sodium hydroxide

Barium tetraoxocarbonate

Answer Details

Mixing aqueous solutions of barium hydroxide and sodium tetraoxocarbonate (IV) would result in a chemical reaction that produces a white precipitate of barium tetraoxocarbonate (IV). The balanced chemical equation for this reaction is: Ba(OH)2(aq) + Na2CO3(aq) → BaCO3(s) + 2NaOH(aq) In the above equation, the barium hydroxide (Ba(OH)2) reacts with sodium tetraoxocarbonate (IV) (Na2CO3) to form barium tetraoxocarbonate (IV) (BaCO3), which is a white precipitate, and sodium hydroxide (NaOH). Therefore, the correct option is 4) Barium tetraoxocarbonate.

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

Acids, Bases And Salts

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Question 26 Report

Which of the following will precipitate in dil. HCl

ZnS

Na2 S

Fe S

CuS

Answer Details

Among the given options, only CuS will precipitate in dilute HCl. CuS is insoluble in dilute HCl, and hence it will precipitate when added to dilute HCl. However, the other options will dissolve in dilute HCl, and hence they will not precipitate. ZnS will dissolve in dilute HCl to form ZnCl2 and H2S. Na2S will react with dilute HCl to produce H2S and NaCl. FeS will dissolve in dilute HCl to form FeCl2 and H2S. Therefore, the correct answer is (4) CuS.

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

Acids, Bases And Salts

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Question 27 Report

On the basis of the electrochemical series, which of these ions will show the greater tendency to be discharged at the cathode in an electrolytic cell

cu

^{2 +}

sn

^{2 +}

fe

^{2 +}

zn

^{2 +}

Answer Details

The electrochemical series is a list of metals and ions arranged in order of their decreasing tendency to lose or gain electrons, and thus, their ability to act as reducing or oxidizing agents. The higher the position of a metal or ion in the electrochemical series, the greater its tendency to lose electrons and undergo oxidation, while the lower its position, the greater its tendency to gain electrons and undergo reduction. In an electrolytic cell, the cathode is the electrode where reduction occurs, meaning that cations (positively charged ions) are attracted and gain electrons to form neutral atoms or molecules. Based on the electrochemical series, the ion with the higher position in the series will have a greater tendency to gain electrons and be discharged at the cathode, while the ion with the lower position will have a lower tendency and may not be discharged at all. Among the given options, the electrochemical series order is: Cu2+ > Sn2+ > Fe2+ > Zn2+ Therefore, Cu2+ has the highest tendency to be discharged at the cathode and undergo reduction, while Zn2+ has the lowest tendency. So, in an electrolytic cell, Cu2+ will be discharged at the cathode, while Zn2+ may not be discharged at all, depending on the conditions of the cell.

Read lesson note on Electrolysis (JAMB)

Read lesson note on Redox Reactions (WAEC)

Electrolysis

Redox Reactions

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Question 28 Report

\(2\mathrm{H}_2 + \mathrm{O}_2 \rightarrow 2\mathrm{H}_2\mathrm{O}\)

From the equation above, calculate the volume of unreacted oxygen gas if a mixture of \(50\mathrm{cm}^3\) of hydroden and \(75\mathrm{cm}^3\) of oxygen are involved

85cm

^{3}

50cm

^{3}

125cm

^{3}

55cm

^{3}

Answer Details

The balanced chemical equation shows that 2 moles of hydrogen gas react with 1 mole of oxygen gas to produce 2 moles of water vapor. Therefore, the stoichiometric ratio of hydrogen to oxygen is 2:1. In this problem, there are 50cm3 of hydrogen gas and 75cm3 of oxygen gas. Since the gases are at the same temperature and pressure, their volumes are directly proportional to the number of moles of gas present. Using the stoichiometric ratio, we can calculate that the amount of oxygen gas required to react completely with 50cm3 of hydrogen gas is (1/2) * 50cm3 = 25cm3. Since there are 75cm3 of oxygen gas present, there must be (75cm3 - 25cm3) = 50cm3 of unreacted oxygen gas remaining. Therefore, the volume of unreacted oxygen gas is 50cm3. Answer: 50cm3

Read lesson note on Stoichiometry And Chemical Reactions (WAEC)

Stoichiometry And Chemical Reactions

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Question 29 Report

Which of the following constitutes a mixture? I. Petroleum II. Rubber latex III. Vulcanizer’s solution IV. Carbon (iv) sulphide

I, II and III

I, II and IV

I and II only

I and IV

Separation Of Mixtures And Purification Of Chemical Substances

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Question 30 Report

There is a large temperature interval between the melting point and the boiling point of metal because:

metals have a very high melting point

metals conduct heat very rapidly

melting does not break the metallic bond but boiling does

the crystal lattice of metal is easily broken

Answer Details

The correct answer is: "melting does not break the metallic bond but boiling does." The metallic bond is the force of attraction between metal atoms, which holds them together to form a solid. When a metal is heated, its temperature increases, and at a certain point, the energy provided by the heat is enough to overcome the metallic bond and cause the metal to melt. However, even in the liquid state, the metallic bond remains intact, which is why metals have a very high melting point. On the other hand, when the temperature is further increased, the energy provided by the heat becomes enough to break the metallic bond, and the metal atoms become completely detached from one another. This results in the metal boiling and turning into a gas. Because the metallic bond is much stronger than other types of intermolecular forces, such as van der Waals forces, it requires a lot of energy to break, resulting in a large temperature interval between the melting point and boiling point of metal.

Read lesson note on Water (JAMB)

Read lesson note on Structure Of The Atom (WAEC)

Water

Structure Of The Atom

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Question 31 Report

In the extraction of iron, hot air is introduced into the blast furnace through?

valves

open-hearths

arcs

tuyeres

Answer Details

In the extraction of iron, hot air is introduced into the blast furnace through tuyeres. Tuyeres are nozzles that are located at the bottom of the blast furnace, and they are used to blow hot air into the furnace. The hot air helps to burn the coke (a fuel made from coal) which provides the heat needed to melt the iron ore. The air also helps to remove the waste gases that are produced during the reaction, allowing the iron to be extracted more efficiently.

Read lesson note on Chemical Equilibria (JAMB)

Chemical Equilibria

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Question 32 Report

The dehydration of \( \mathrm{CH_3CH_2CH_2CH_2OH} \) will give?

HC≡CCH

_{2}

CH

_{3}

CH

_{2}

≡CH

_{2}

CH

_{3}

CH

_{3}

C≡CCH

_{3}

CH

_{3}

CH=CHCH

_{3}

Chemistry Of Carbon Compounds (Nigeria Only)

View Answer

Question 33 Report

Ethene, when passed into concentrated H2SO4, is rapidly absorbed. The product is diluted with water and then warmed to produce

Ethanol

diethyl ether

ethanal

diethyl sulphate

Answer Details

When ethene is passed into concentrated H2SO4, it undergoes electrophilic addition reaction to form ethyl hydrogen sulfate as the product. The reaction mixture is then diluted with water and warmed to produce ethanol as the main product. Therefore, the answer is ethanol.

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Question 34 Report

Hard water is water with high concentrations of dissolved ions, in particular calcium and

magnesium ions

nitrogen ions

phosporus ions

helium ions

Answer Details

Hard water is water that contains high amounts of dissolved minerals, specifically calcium and magnesium ions. These minerals come from the rocks and soil that the water flows through and can accumulate in the water as it travels to your home. When you use hard water, it can leave mineral deposits on your pipes, fixtures, and appliances, which can reduce their efficiency and lifespan. It can also make soap less effective and leave your skin feeling dry and itchy. Therefore, it is important to treat hard water if it is a problem in your area.

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

Solubility Of Substances (Ghana Only)

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Question 35 Report

Wrought iron is obtained by heating cast iron in a furnace with?

magnetite

haematite

carbon(ii)oxide

calcium trioxosilicate(iv)

Answer Details

Wrought iron is a type of iron that is very malleable and ductile, meaning it can be easily shaped and formed into various objects. It is obtained by heating cast iron in a furnace with haematite, also known as iron(III) oxide. When cast iron is heated with haematite in a furnace, a chemical reaction takes place where the haematite reacts with the carbon in the cast iron to produce carbon dioxide gas. This reaction also produces molten iron, which is then further heated to remove any impurities like sulfur and phosphorus. This molten iron is then poured into molds to form ingots of wrought iron. Therefore, haematite is essential in the process of obtaining wrought iron from cast iron.

Read lesson note on Metals And Their Compounds (JAMB)

Metals And Their Compounds

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Question 36 Report

The reactions below represent neutralization reaction, in which of them is the value of ΔH highest?

CH

_{3}

CH

_{2}

COOH + KOH → CH

_{3}

CH

_{2}

COOK + H

_{2}

O

NH

_{4}

OH + HCL → NH

_{4}

+ H

_{2}

O

NaOH + HCL → NaCL + H

_{2}

O

CH

_{3}

COOH + NaOH → CH

_{3}

COONa + H

_{2}

O

Answer Details

The reaction with the highest ΔH (change in enthalpy) would be the reaction between HCL and NaOH, which forms NaCL and H2O. This is because the formation of water releases energy in the form of heat, which is reflected in the positive ΔH value for this reaction. When an acid and a base react, they neutralize each other and form a salt and water, with the release of heat being a sign of an exothermic reaction.

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Environmental Pollution

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Question 37 Report

The oxidation number of oxygen in BaO2 is

-2

-4

-1

0

Answer Details

To determine the oxidation number of oxygen in BaO2, we can use the fact that the overall charge of a compound must be zero. Barium (Ba) is a Group 2 element and has an oxidation state of +2. The compound BaO2 has no net charge, so the sum of the oxidation states of all the atoms must be zero. Let x be the oxidation state of oxygen in BaO2. Therefore, we have: (+2) + 2(x) = 0 Solving for x, we get: x = -1 Therefore, the oxidation number of oxygen in BaO2 is -1.

Read lesson note on Oxidation And Reduction (JAMB)

Read lesson note on Redox Reactions (WAEC)

Oxidation And Reduction

Redox Reactions

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Question 38 Report

Addition of sodium chloride to water to form a solution would lead to?

increase in freezing point and increase the boiling point

increase in freezing point and decrease the boiling point

decrease in freezing point and decrease the boiling point

decrease in freezing point and increase the boiling point

Answer Details

The addition of sodium chloride to water to form a solution would lead to a decrease in freezing point and an increase in boiling point. This effect is known as colligative properties, which depend on the concentration of solute particles in a solution. When sodium chloride dissolves in water, it breaks down into sodium ions and chloride ions. These ions occupy space between water molecules and interfere with the formation of ice crystals during freezing. As a result, the freezing point of the solution is lowered below that of pure water. This is why we use salt to de-ice roads and sidewalks during the winter season. Similarly, the presence of solute particles in a solution also raises the boiling point of the solution. The increased concentration of solute particles in the solution causes a decrease in the vapor pressure of the solvent (water), making it harder for the solvent molecules to escape into the gas phase. This means that more energy is required to bring the solution to its boiling point compared to pure water. In summary, the addition of sodium chloride to water forms a solution with lower freezing point and higher boiling point compared to pure water.

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Solubility Of Substances (Ghana Only)

Solutions

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Question 39 Report

Silver chloride turns gray when exposed to sunlight because

the silver ion is reduced to silver

the silver io is oxidized to silver

silver is transition metal

the silver chloride forms complexes in the sun

Oxidation And Reduction

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Question 40 Report

Crude petroleum is converted to useful products by the process of?

fractional crystallization

fractional distillation

filtration

chromatography

Answer Details

The process of converting crude petroleum into useful products is known as fractional distillation. Crude petroleum is a mixture of different hydrocarbons, and fractional distillation separates these hydrocarbons based on their boiling points. During the process of fractional distillation, crude petroleum is heated to a high temperature, and the resulting vapors are passed through a tower called a fractionating column. This column contains a series of trays, and each tray contains a specific temperature range. As the vapors rise up the column, they cool and condense into liquids on the tray with a temperature that matches their boiling point. The liquids are then collected and further refined into useful products like gasoline, diesel, jet fuel, and heating oil. Fractional distillation is an important process because it allows us to separate and purify the different components of crude petroleum, which have different properties and uses. For example, gasoline has a lower boiling point and is more volatile than diesel fuel, which makes it ideal for use in cars. By separating these components, we can create products that meet specific needs and requirements.

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Solubility

Introduction To Chemistry

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