The choice of method for extracting a metal from its ores depends on the

position of the metal in the electrochemical series

position of the metal in the periodic table

The ionic radii of metals are usually

greater than their atomic radii

unaffected by the charge on the ion

Suitable reagents for the laboratory preparation nitrogen are

sodium dioxonitrate(III) and ammonium chloride

sodium trioxonitrate(V) and ammonium chloride

sodium chloride and ammonium trioxonitrate(V)

sodium chloride and ammonium di-ozonitrate(III)

The collision theory explains reaction rates in terms of

frequency of collision of the reactants

frequency of collision of the products

Which of the following is an example of a chemical change?

separating a mixture by distillation

The conductivity of an acid solution depends on the

amount of ions present and their mobilities

Elements P, Q, R, S have 6, 11, 15, 17 electrons respectively, therefore,

Q will form an electrovalent bond with S

P will form an electrovalent bond with R

Q will form a covalent bond with S

R will form an electrovalent bond with S

Q will form an electrovalent bond with S

In the laboratory preparation of oxygen, the gas cannot be collected by displacement of air because

the density of oxygen is greater than that of air

the density of air is nearly the same as that of oxygen

JAMB UTME - Chemistry - 2018 | Green Bridge CBT

Question 1 Report

2KClO3(g) MNO3? 2KCl(s) + 3O2(g)

The importance of the catalyst in the reaction above is that

heating may not be required before the reaction takes place

the reaction is controllable even at a high temperature

the reaction produces large quantity of oxygen

the reaction takes place more rapidly at a lower temperature

Stoichiometry And Chemical Reactions

View Answer

Question 2 Report

Calculate the percentage composition of oxygen in calcium trioxocarbonate(IV) [Ca=40, C=12, O=16]

16

48

40

12

Answer Details

To calculate the percentage composition of oxygen in calcium trioxocarbonate(IV), we first need to determine the molar mass of the compound. The compound has one calcium atom (Ca), one carbon atom (C), and three oxygen atoms (O). So, the molar mass of calcium trioxocarbonate(IV) can be calculated as follows: Molar mass = (1 × atomic mass of Ca) + (1 × atomic mass of C) + (3 × atomic mass of O) = (1 × 40) + (1 × 12) + (3 × 16) = 40 + 12 + 48 = 100 g/mol Next, we need to determine the mass of oxygen in one mole of calcium trioxocarbonate(IV). The compound has three oxygen atoms, each with an atomic mass of 16 g/mol. Therefore, the total mass of oxygen in one mole of the compound is: Mass of oxygen = 3 × 16 = 48 g/mol Finally, to determine the percentage composition of oxygen in calcium trioxocarbonate(IV), we divide the mass of oxygen by the molar mass of the compound and multiply by 100. Percentage of oxygen = (Mass of oxygen / Molar mass of compound) × 100 = (48 / 100) × 100 = 48% Therefore, the correct answer is 48, which represents the percentage composition of oxygen in calcium trioxocarbonate(IV).

Read lesson note on Chemical Combination (JAMB)

Chemical Combination

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Question 3 Report

In electrovalency, the oxidation number of the participating metal is always

decreasing

increasing

constant

neutral

View Answer

Question 4 Report

Beryllium and Aluminium have similar properties because they

are both metals

belong to the same group

belong to the same period

are positioned diagonally to each other

Metals And Their Compounds

Non-metals And Their Compounds

View Answer

Question 5 Report

Methanoic acid mixes with water in all proportions and has about the same boiling point as water. Which of the following methods would you adopt to obtain pure water from a mixture of Sand, water and methanoic acid?

Fractional distillation

Filtration followed by distillation

Neutralization with sodium hydroxide followed by distillation

Neutralization with sodium hydroxide followed by filtration

Acids, Bases And Salts (Ghana Only)

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Question 6 Report

A balanced chemical equation obeys the law of

conservation of mass

definite proportions

multiple proportions

conservation of energy

Answer Details

A balanced chemical equation obeys the law of conservation of mass. This means that in a chemical reaction, the total mass of the reactants must be equal to the total mass of the products. In other words, atoms cannot be created or destroyed during a chemical reaction, only rearranged. For example, if we burn a piece of wood, the mass of the ashes and the gases released will be equal to the mass of the original wood. This is because the atoms in the wood (carbon, hydrogen, oxygen, etc.) are rearranged during the burning process to form new molecules, but the total number of atoms remains the same. By balancing a chemical equation, we ensure that the same number and type of atoms are present on both sides of the equation, which satisfies the law of conservation of mass.

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

Read lesson note on Stoichiometry And Chemical Reactions (WAEC)

Kinetic Theory Of Matter And Gas Laws

Stoichiometry And Chemical Reactions

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Question 7 Report

(I). \(3\mathrm{CuO}(s) + 2\mathrm{NH}_3(g) \longrightarrow 3\mathrm{Cu}(s) + 3\mathrm{H}_2\mathrm{O}(l) + \mathrm{N}_2(g)\)

(II). \(2\mathrm{NH}_3(g) + 3\mathrm{Cl}_2(g) \longrightarrow 6\mathrm{HCl}(g) + \mathrm{N}_2(g)\)

(III). \(4\mathrm{NH}_3(g) + 3\mathrm{O}_2(g) \longrightarrow 6\mathrm{H}_2\mathrm{O}(l) + \mathrm{N}_2(g)\)

The reactions represented by the equations above demonstrate the

basic properties of ammonia

acidic properties of ammonia

reducing properties of ammonia

oxidizing properties of ammonia

Chemical Combination

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Question 8 Report

The solubility of the solids that dissolves in a given solvent with the liberation of heat will

increase with an increase in temperature

decrease with an increase in temperature

decrease with a decrease in temperature

not be affected by changes in temperature

Answer Details

The solubility of solids in a given solvent is the amount of solid that can dissolve in the solvent to form a solution. When a solid dissolves in a solvent, it releases heat. The solubility of the solid in the solvent can be affected by changes in temperature. Generally, when the temperature of a solution increases, the solubility of the solid in the solvent increases as well. This is because the increased heat energy makes it easier for the solid particles to separate and dissolve in the solvent. As a result, the solubility of the solid in the solvent will increase with an increase in temperature. On the other hand, if the temperature decreases, the solubility of the solid in the solvent decreases. This is because the decreased heat energy makes it harder for the solid particles to separate and dissolve in the solvent. As a result, the solubility of the solid in the solvent will decrease with a decrease in temperature. In summary, the solubility of solids in a given solvent will generally increase with an increase in temperature and decrease with a decrease in temperature.

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

Solubility Of Substances (Ghana Only)

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Question 9 Report

The derivative of benzene that can be used in making explosives is

aniline

xylene

phenol

toluene

Chemistry Of Carbon Compounds (Nigeria Only)

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Question 10 Report

\( \mathrm{H_2S(g) + Cl_2(g) \rightarrow 2HCl(g) + S(g)} \)

In the reaction above, the substance that is reduced is

H

_{2}

S

HCl

Cl

_{2}

Oxidation And Reduction

View Answer

Question 11 Report

Which of these sources of water may likely contain the least concentration of Ca\(^{2+}\) and Mg\(^{2+}\)?

Spring water

River water

Tap water

Sea water

Answer Details

The source of water that is likely to contain the least concentration of Ca2+ and Mg2+ is tap water. Tap water is treated and processed before it is made available for consumption, which often involves removing minerals such as calcium and magnesium. Spring water and river water, on the other hand, are naturally occurring and generally contain higher levels of minerals. Sea water has the highest concentration of minerals, including Ca2+ and Mg2+.

Read lesson note on Water (JAMB)

Water

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Question 12 Report

An aqueous solution of a metal salt, M. gives a white precipitate with NaOH which dissolves in excess NaOH. With aqueous ammonia, the solution of M also gives a white precipitate which dissolves in excess ammonia Therefore the cation in M is

Zn

Ca

Al

Po

Chemical Bonds (Nigeria Only)

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Question 13 Report

The figure above shows the electrolysis of molten sodium chloride. Z is the

anode where the Cl

^{-}

ions are oxidized

cathode where the Cl

^{-}

ions are reduced

anode where the Na

^{+}

ions are reduced

cathode where the Na

^{+}

ions are oxidized

Answer Details

The figure shows the electrolysis of molten sodium chloride. During electrolysis, an electric current is passed through a molten or dissolved ionic compound to separate the ions. The positive ions move towards the negative electrode (cathode) and the negative ions move towards the positive electrode (anode). In the figure, the electrode connected to the positive terminal of the battery is the anode and the electrode connected to the negative terminal is the cathode. At the anode, the negatively charged chloride ions (Cl-) lose electrons and are oxidized to form chlorine gas (Cl2). At the cathode, the positively charged sodium ions (Na+) gain electrons and are reduced to form liquid sodium metal (Na). Therefore, the answer is (a) anode where the Cl- ions are oxidized. Z is the anode in the figure.

Read lesson note on Electrolysis (JAMB)

Electrolysis

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Question 14 Report

When large hydrocarbon molecules are heated at high temperature in the presence of a catalyst to give smaller molecules, the process is known as

disintegration

polymerization

cracking

degradation

Answer Details

The process of breaking down large hydrocarbon molecules into smaller molecules by heating them at high temperatures in the presence of a catalyst is known as cracking. This process is used to convert heavy, high-molecular-weight hydrocarbon molecules into lighter, more valuable products such as gasoline and diesel fuel. The high temperatures cause the large molecules to break apart into smaller ones, and the catalyst helps speed up the reaction. This process is important in the petrochemical industry, as it allows for the production of a wider range of useful products from crude oil.

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

Chemistry Of Carbon Compounds (Ghana Only)

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Question 15 Report

Which of the following produces relatively few ions in solution?

NaOH

Ca(OH)

_{2}

KOH

AI(OH)

_{3}

Answer Details

The correct answer is AI(OH)3. When ionic compounds dissolve in water, they dissociate into their constituent ions, producing charged particles in solution. The more ions a compound produces, the more conductive it is in solution. AI(OH)3, also known as aluminum hydroxide, produces relatively few ions in solution because it is a weak base. When AI(OH)3 dissolves in water, it releases a small amount of Al3+ and OH- ions. In contrast, NaOH, KOH, and Ca(OH)2 are strong bases that dissociate more completely in water and produce more ions in solution. NaOH and KOH produce one hydroxide ion for every sodium or potassium ion, while Ca(OH)2 produces two hydroxide ions for every calcium ion. Therefore, of the options listed, AI(OH)3 produces relatively few ions in solution.

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

Acids, Bases And Salts (Ghana Only)

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Question 16 Report

If 1 litre of 2.2M sulphuric acid is poured into a bucket containing 10 litres of water and the resulting solution mixed thoroughly, the resulting sulphuric acid concentration will be

2.2M

1.1M

0.22M

0.11M

Answer Details

When 1 liter of 2.2M sulphuric acid is added to 10 liters of water, the total volume of the resulting solution is 11 liters. To find the resulting concentration of sulphuric acid, we need to use the equation: M1V1 = M2V2 where M1 is the initial concentration, V1 is the initial volume, M2 is the final concentration, and V2 is the final volume. We can plug in the values we know: M1 = 2.2M (the initial concentration of the sulphuric acid) V1 = 1L (the initial volume of the sulphuric acid) M2 = ? (the final concentration we're trying to find) V2 = 11L (the final volume of the resulting solution) Solving for M2, we get: M2 = (M1 x V1) / V2 M2 = (2.2M x 1L) / 11L M2 = 0.2M Therefore, the resulting sulphuric acid concentration is 0.2M or 0.2 moles per liter. In summary, when 1 liter of 2.2M sulphuric acid is mixed with 10 liters of water, the resulting sulphuric acid concentration is diluted to 0.2M. This is because the total volume of the resulting solution is greater than the initial volume of the sulphuric acid, which leads to a decrease in concentration.

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

Acids, Bases And Salts (Ghana Only)

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Question 17 Report

The hydrogen ion concentration of a sample of orange juice is 2.0 X 10\(^{-11}\)moldm\(^{-3}\). What is its p\(^{OH}\)? [log102 = 0.3010]

3.30

13.00

10.70

11.30

Acids, Bases And Salts (Ghana Only)

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Question 18 Report

The Sulphide which is insoluble in dilute hydrochloric acid is

FeS

CuS

ZnS

Na2S

Answer Details

The sulphide which is insoluble in dilute hydrochloric acid is Copper Sulphide (CuS). When metal sulphides react with hydrochloric acid, they undergo an acid-base reaction to produce hydrogen sulphide gas and the corresponding metal chloride. For example, when Iron Sulphide (FeS) reacts with hydrochloric acid, it forms hydrogen sulphide gas (H2S) and iron chloride (FeCl2) as follows: FeS + 2HCl → H2S + FeCl2 However, Copper Sulphide (CuS) does not react with dilute hydrochloric acid, as it is insoluble in this acid. This is due to the fact that CuS is a much less reactive metal sulphide compared to FeS and ZnS, and therefore it does not undergo an acid-base reaction with dilute hydrochloric acid. In summary, CuS is the sulphide which is insoluble in dilute hydrochloric acid due to its low reactivity with acids.

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 19 Report

A sample of hard water contains some calcium sulphate and calcium hydrogen carbonate. The total hardness may therefore be removed by

boiling the water

adding excess calcium hydroxide

adding a calculated amount of calcium hydroxide

adding sodium carbonate

Acids, Bases And Salts (Ghana Only)

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Question 20 Report

The presence of ammonia gas in a desiccator can exclusively be removed by

phosphorus (V) oxide

fused calcium chloride

calcium chloride

concentrated tetraoxosulphate (VI) acid

Oxidation And Reduction

Acids, Bases And Salts (Ghana Only)

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Question 21 Report

\(3\mathrm{H}_2(g) + \mathrm{N}_2 \rightleftharpoons 2\mathrm{NH}_3(g)\); H= -ve

In the reaction above, lowering of temperature will

have no effect on the equilibrium position

increase the rate of both the forward and reverse reactions equally

favour the forward reactio

favour the reverse reaction

Chemical Kinetics And Equilibrium Systems (Ghana Only)

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Question 22 Report

According to the Kinetic Theory an increase in temperature causes the kinetic energy of particles to

decrease

increase

be zero

remain constant

Answer Details

The kinetic energy of particles increases with an increase in temperature. In the Kinetic Theory, temperature is related to the average kinetic energy of the particles in a substance. The higher the temperature, the faster the particles move, and the more energy they have. Think of it like this: if you throw a ball, it will have more energy and travel farther if you throw it harder. Similarly, if you heat up a substance, its particles will move faster and have more energy. So, the answer is that an increase in temperature causes the kinetic energy of particles to increase.

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

Kinetic Theory Of Matter And Gas Laws

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Question 23 Report

A substance that is used as a ripening agent for fruits is

ethene

propane

methane

butane

Answer Details

The substance that is commonly used as a ripening agent for fruits is ethene. Ethene, also known as ethylene, is a natural plant hormone that is produced by fruits, especially during the ripening process. It is a colorless gas that can be easily synthesized and used as a ripening agent for fruits. When fruits are exposed to ethene, it triggers a series of biochemical reactions that accelerate the natural ripening process. This can help fruits to ripen faster and more uniformly, which is important for commercial purposes where fruits need to be sold quickly. The use of ethene as a ripening agent is regulated by food safety agencies, as excessive exposure to ethene can cause over-ripening and spoilage of fruits. However, when used in appropriate concentrations, ethene is a safe and effective way to promote the ripening of fruits.

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

Acids, Bases And Salts

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Question 24 Report

The general formula of alkanones is

RCHO

R

_{2}

CO

RCOOH

RCOOR

Chemistry Of Carbon Compounds (Nigeria Only)

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Question 25 Report

In the preparation of oxygen by heating KCIO\(_2\), in the presence of MnO\(_2\) only moderate heat is needed because the catalyst acts by

lowering the pressure of the reaction

increasing the surface area of the reaction

increasing the rate of the reaction

lowering the energy barrier of the reaction

Answer Details

The presence of MnO2 acts as a catalyst in the reaction of KCIO2 to produce oxygen. A catalyst is a substance that increases the rate of a chemical reaction without being consumed in the reaction itself. MnO2 acts by lowering the energy barrier of the reaction, which means it reduces the amount of energy required for the reaction to take place. This makes it easier for the reaction to occur, and thus the reaction proceeds at a faster rate. As a result, only moderate heat is needed to provide the initial energy required for the reaction to start. Therefore, the correct answer is: lowering the energy barrier of the reaction.

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

Kinetic Theory Of Matter And Gas Laws

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Question 26 Report

What mass of Cu would be produced by the cathodic reduction of \(\mathrm{Cu}^{2+}\) when 1.60A of current passes through a solution of \(\mathrm{CuSO}_{4}\) for 1 hour. (F=96500Cmol\(^{-1}\), Cu=64)

7.64g

3.82g

1.91g

0.96g

Answer Details

The reduction reaction that occurs at the cathode during the electrolysis of CuSO4" tabindex="0" class="mjx-chtml MathJax_CHTML" id="MathJax-Element-1-Frame">4, is: Cu2+" tabindex="0" class="mjx-chtml MathJax_CHTML" id="MathJax-Element-2-Frame">2+ + 2e- -> Cu(s) From this, we can see that each Cu2+ ion requires two electrons to be reduced to copper metal. Given the current (I = 1.60 A), time (t = 1 hour = 3600 s), and Faraday's constant (F = 96500 C/mol), we can calculate the total amount of charge that passes through the solution: Q = I*t = 1.60 A * 3600 s = 5760 C Using Faraday's law, we can relate the amount of charge that passes through the solution to the number of moles of electrons transferred during the reduction reaction: n = Q/F = 5760 C / 96500 C/mol = 0.0597 mol e- Since each Cu2+ ion requires 2 electrons to be reduced to copper metal, the number of moles of copper produced is half the number of moles of electrons transferred: mol Cu = 0.0597 mol e- / 2 = 0.0299 mol Cu Finally, we can convert the moles of copper produced to grams using the molar mass of copper: mass Cu = 0.0299 mol Cu * 64 g/mol = 1.91 g Therefore, the answer is 1.91 g of Cu produced. is correct.

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

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

Read lesson note on Energy And Energy Changes (WAEC)

Kinetic Theory Of Matter And Gas Laws

Chemical Bonds (Nigeria Only)

Energy And Energy Changes

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Question 27 Report

In the upper atmosphere, the ultra-violet light breaks off a free chlorine atom from chlorofluorocarbon molecule. The effect of this is that the free chlorine atom will

be very reactive and will attack ozone

be non-reactive and will not attack ozone

not change the level of ozone in the atmosphere

increase the level of ozone in the atmosphere

Answer Details

The free chlorine atom that breaks off from a chlorofluorocarbon molecule will be very reactive and will attack ozone in the upper atmosphere. Ozone is a molecule made up of three oxygen atoms, and when the free chlorine atom reacts with ozone, it breaks the ozone molecule into two separate oxygen molecules. This reaction reduces the amount of ozone in the atmosphere, which is known as ozone depletion. Over time, this can lead to a thinning of the ozone layer, which protects life on Earth from harmful ultraviolet radiation from the sun.

Read lesson note on Environmental Pollution (JAMB)

Environmental Pollution

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Question 28 Report

How many atoms are present in 6.0g of magnesium? [Mg = 24, N.A = \(6.02 \times 10^{23}\) mol]

1.20 x 10

^{22}

2.4 x 10

^{22}

1.51 x 10

^{22}

3.02 x 10

^{22}

Atomic Structure And Bonding

View Answer

Question 29 Report

Which of the following are mixtures?

I. Petroleum

II. Rubber latex

III. Vulcanizer's solution

IV. Carbon sulphide

I, II and III

I, II and IV

I and II only

I and IV

Separation Of Mixtures And Purification Of Chemical Substances

View Answer

Question 30 Report

A quantity of electricity liberates 3.6g of Silver from its salt. What mass of aluminium Will be liberated from its salt by the same quantity of electricity? [Al = 27, Ag = 108].

2.7g

1.2g

0.9g

0.3g

Answer Details

The amount of substance liberated at an electrode during electrolysis is directly proportional to the quantity of electricity passed through the solution. This is known as Faraday's laws of electrolysis. The key to solving this problem is to recognize that the same quantity of electricity is used to liberate both silver and aluminum from their respective salts. We can use the ratio of their molar masses to determine the mass of aluminum liberated. The molar mass of silver (Ag) is 108 g/mol, while the molar mass of aluminum (Al) is 27 g/mol. This means that it takes four times as many moles of aluminum to make the same mass as one mole of silver. Since the same quantity of electricity liberates 3.6g of silver from its salt, it will liberate four times as many moles of aluminum. Therefore, the mass of aluminum liberated is: (4 moles of Al) x (27 g/mol) = 108 g So, the mass of aluminum liberated is 0.108 g, or 0.1 g to one significant figure. Therefore, the answer is option D: 0.3g.

Read lesson note on Electrolysis (JAMB)

Electrolysis

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Question 31 Report

Which of these alloys contains copper?

solder

steel

permallory

bronze

Answer Details

Bronze is the alloy that contains copper. Bronze is a metal alloy composed of copper and typically other elements such as tin, aluminum, silicon, or nickel. It is known for its strength, durability, and corrosion resistance. In fact, bronze is one of the earliest alloys created by humans, and it has been used for thousands of years to make tools, weapons, and decorative objects. Solder is an alloy of lead, tin, and sometimes other metals that is used to join metals together by melting the solder and allowing it to flow into the joint. Steel is an alloy of iron and carbon, and sometimes other elements like chromium, nickel, or manganese, that is known for its strength and durability. Permallory is a nickel-iron alloy with high magnetic permeability and low coercive force, which makes it useful in the production of electrical and electronic equipment. None of these alloys contain copper.

Read lesson note on Metals And Their Compounds (JAMB)

Metals And Their Compounds

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Question 32 Report

An element X forms the following compounds with chlorine; \( \mathrm{XCl_4} \), \( \mathrm{XCl_3} \), \( \mathrm{XCl_2} \). This illustrates the

law of multiple proportions

law of chemical proportions

law of simple proportions

law of conservation of mass

Answer Details

The element X forming different compounds with chlorine (XCl4, XCl3, and XCl2) illustrates the law of multiple proportions. This law states that when two elements combine to form more than one compound, the ratio of the masses of one element that combine with a fixed mass of the other element is always a whole number ratio. In this case, the ratio of chlorine to X in the different compounds (XCl4, XCl3, and XCl2) is 4:1, 3:1, and 2:1, respectively, which are all whole number ratios.

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

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

Kinetic Theory Of Matter And Gas Laws

Acids, Bases And Salts (Ghana Only)

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Question 33 Report

The lUPAC name for

1-methyl pentane

3-methylbutane

2-methylbutane

1-dimethyl propane

View Answer

Question 34 Report

The alkanoic acid found in human sweat is

CH

_{3}

-COOH

CH

_{3}

—CH

_{2}

—COOH

H-COOH

CH

_{3}

Answer Details

The alkanoic acid found in human sweat is CH3CH2COOH, also known as propionic acid. Sweat is composed of various substances such as water, electrolytes, and waste products. One of these waste products is an oily substance called sebum, which is secreted by the sebaceous glands in the skin. When sebum breaks down, it forms various fatty acids, including propionic acid. Propionic acid has a slightly pungent odor, which is why sweat can sometimes smell sour or cheesy. However, the presence of propionic acid in sweat is actually beneficial, as it has antimicrobial properties that help to prevent the growth of harmful bacteria on the skin. In summary, the alkanoic acid found in human sweat is propionic acid, which is a fatty acid produced when sebum breaks down. Its antimicrobial properties help to keep the skin healthy.

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

Acids, Bases And Salts

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Question 35 Report

A basic postulate of the kinetic theory of gases is that the molecules of a gas move in straight lines between collisions. This implies that

collisions are perfectly elastic

forces of repulsion exis

forces of repulsion and attraction are in equilibrium

collisions are inelastic

Kinetic Theory Of Matter And Gas Laws

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Question 36 Report

During the electrolysis of copper II sulphate between platinum electrodes, if litmus solution is added to the anode compartment

the litmus turns blue but no gas is evolved

the litmus turns blue and oxygen is evolved

the litmus turns blue and hydrogen is evolved

the litmus turns red and oxygen is evolved

Answer Details

During the electrolysis of copper II sulphate between platinum electrodes, if litmus solution is added to the anode compartment, the litmus will turn red and oxygen gas will be evolved. This is because during electrolysis, the positively charged copper ions (Cu2+) in the copper II sulphate solution are attracted to the negative cathode electrode, where they gain electrons and are reduced to form solid copper. At the same time, the negatively charged sulphate ions (SO42-) are attracted to the positive anode electrode, where they lose electrons and are oxidized to form oxygen gas and water. The litmus added to the anode compartment turns red because of the formation of oxygen gas, which is a highly reactive oxidizing agent that can react with the litmus to cause it to turn red. No hydrogen gas is evolved because hydrogen is produced at the cathode, which is in a separate compartment from the anode where the litmus is added.

Read lesson note on Electrolysis (JAMB)

Electrolysis

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Question 37 Report

The situation obtained when a perfect gas expands into a vacuum is

ΔH is positive and TΔ S is zero

ΔH is positive and T Δ S is negative

ΔH is negative and TΔ S is zero

ΔH is zero and T Δ S is positive

Kinetic Theory Of Matter And Gas Laws

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Question 38 Report

Which of the compounds is composed of Al, Si, O and H?

Epson salt

Limestone

Clay

Urea

Answer Details

The compound composed of Al, Si, O and H is clay. Clay is a type of sedimentary rock that is made up of very small mineral particles, including hydrated aluminum silicates and other minerals such as quartz and feldspar. These minerals are rich in aluminum, silicon, oxygen, and hydrogen, which gives clay its unique chemical composition. Clay is formed through a process of weathering and erosion of rocks containing these minerals over a long period of time. As water and other natural forces break down the rocks, the mineral particles become suspended in water and are eventually deposited in sedimentary layers. Over time, these layers become compacted and cemented together, forming the solid clay deposits we see today. Therefore, the answer is option C: Clay.

Read lesson note on Chemical Combination (JAMB)

Chemical Combination

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Question 39 Report

An element used in the production of matches is

nitrogen

aluminium

copper

sulphur

Answer Details

The element used in the production of matches is sulphur. Matches are small sticks made of wood or cardboard with a chemical mixture at one end. This chemical mixture, called the match head, contains several compounds including sulphur. When the match is struck against a rough surface, the friction generates heat that ignites the sulphur in the match head, causing a flame. This flame then ignites the other compounds in the match head, which in turn ignites the wood or cardboard stick. Sulphur is an important component of the match head because it is highly flammable and burns easily. It also helps to ignite the other compounds in the match head. However, sulphur by itself is not a good fuel, which means that it cannot sustain a flame on its own. Therefore, it needs other combustible materials, such as potassium chlorate or phosphorus, to make the match head burn. Overall, sulphur plays a crucial role in the chemistry of matches and allows us to easily start fires for various purposes.

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

Non-metals And Their Compounds

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Question 40 Report

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

1

2

3

4

Answer Details

The number of electrons in the valence shell of an element can be determined by using the periodic table and the electron configuration of the element. The valence shell is the outermost shell that contains electrons that are involved in chemical reactions. For an element with atomic number 14, which is silicon, the electron configuration is 1s2 2s2 2p6 3s2 3p2. The valence shell of silicon is the third shell, which contains 3s2 and 3p2 electrons. Therefore, the number of electrons in the valence shell of silicon is 4 electrons.

Read lesson note on Atomic Structure And Bonding (JAMB)

Atomic Structure And Bonding

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