JAMB UTME - Chemistry - 2018

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Question 5 Report

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

dissolution of salt in water

rusting of iron

melting of ice

separating a mixture by distillation

Acids, Bases And Salts

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Question 6 Report

What is the PH of 0.00 1 moldm\(^{3}\) solution of the sodium hydroxide

14

13

12

11

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Question 7 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

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Question 8 Report

The periodic classification is an arrangement of the elements

atomic weights

isotopic weights

molecular weights

atomic numbers

Answer Details

The periodic classification is an arrangement of the elements based on their atomic numbers. The periodic table is a chart that lists all the known chemical elements in order of increasing atomic number, arranged in rows and columns according to their electronic structure and chemical properties. The atomic number of an element is the number of protons in the nucleus of an atom of that element. Each element has a unique atomic number, which determines its position in the periodic table. The elements are arranged in rows called periods, and in columns called groups or families. Elements in the same group have similar properties because they have the same number of valence electrons, which are the electrons in the outermost shell of the atom. The periodic table is an incredibly useful tool for chemists because it allows them to predict the properties of elements based on their position in the table. For example, elements in the same group tend to form similar compounds, so if you know the properties of one element in a group, you can often predict the properties of the other elements in that group. In summary, the periodic classification is an arrangement of the elements based on their atomic numbers. The periodic table is a chart that organizes the elements into rows and columns based on their electronic structure and chemical properties, allowing scientists to make predictions about the behavior of the elements based on their position in the table.

Read lesson note on Atomic Structure And Bonding (JAMB)

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Question 9 Report

A given amount of gas occupies \(10.0\mathrm{dm}^{5}\) at 4atm and 273°C. The number of moles of the gas present is [Molar volume of gas at s.t.p = \(22.4\mathrm{dm}^{3}\)]

0.89 mol

1.90 mol

3.80 mol

5.70 mol

Answer Details

The ideal gas law is PV = nRT, where P is pressure, V is volume, n is the number of moles, R is the gas constant, and T is temperature. We can use this equation to solve for the number of moles of gas present. First, we need to convert the volume from dm5 to dm3, which is the same as liters (L). So, 10.0 dm5 is equal to 10.0/1000 = 0.01 dm3 or 0.01 L. Next, we need to convert the temperature from Celsius to Kelvin by adding 273 to get 546 K. Now we can plug in the values we have into the ideal gas law: 4 atm x 0.01 L = n x 0.0821 L·atm/K·mol x 546 K Simplifying, we get: 0.04 = n x 44.8 Solving for n, we get: n = 0.04/44.8 = 0.00089 mol Finally, we can compare this value to the molar volume of a gas at standard temperature and pressure (STP), which is 22.4 L/mol. To do this, we need to convert the volume of gas we have to STP conditions. Since the temperature is already at STP (273 K), we just need to adjust the pressure. Using the ideal gas law, we can solve for the volume at STP: 1 atm x V = 0.00089 mol x 0.0821 L·atm/K·mol x 273 K Simplifying, we get: V = 0.0224 L or 22.4 dm3 Therefore, the amount of gas present is equal to 0.00089 mol, which is less than 1 mol. So the answer is 0.89 mol.

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

Read lesson note on Stoichiometry And Chemical Reactions (WAEC)

Read lesson note on States Of Matter (WAEC)

Stoichiometry And Chemical Reactions

States Of Matter

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Question 10 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 11 Report

The elements in the periodic table are listed in order of increasing

relative atomic number

atomic mass

relative isotopic mass

nuclear charge

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Question 12 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)

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Question 13 Report

In the shown experiment (Fig. 1) the litmus paper will initially

be bleached

turn green

turn red

turn blue

Acids, Bases And Salts

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Question 14 Report

At what temperature is the solubility of potassium trioxonitrate(V ) equal to that of sodium trioxonitrate (V)?

0

^{o}

c

30

^{o}

c

40

^{o}

c

45

^{o}

c

Solubility

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Question 15 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 16 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 17 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

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Question 18 Report

Diamond is a bad conductor of electricity because its bonding electrons are used in

crystal lattice formation

covalent bond formation

metallic bond formation

coordinate bond formation

Answer Details

Diamond is a bad conductor of electricity because of its unique structure and bonding. The carbon atoms in diamond form a covalent network, where each carbon atom is bonded to four other carbon atoms. These bonds are strong and hold the atoms in a rigid three-dimensional structure called a crystal lattice. In a covalent bond, atoms share electrons to form a stable compound. In diamond, each carbon atom shares its valence electrons with four neighboring carbon atoms, forming a very strong covalent bond. All the valence electrons in the crystal lattice are used in covalent bond formation, which means there are no free or mobile electrons to carry an electric current. In other words, the electrons are tightly held in the covalent bonds, making it difficult for them to move around the crystal lattice and conduct electricity. In contrast, metals conduct electricity well because they have delocalized or free electrons that can move through the lattice of positively charged ions. So, diamond, being a covalent network solid, does not have free electrons that can carry an electric current, which is why it is a bad conductor of electricity.

Read lesson note on Atomic Structure And Bonding (JAMB)

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Question 19 Report

The boiling of fat and aqueous caustic soda is referred to as

hydrolysis

esterification

acidification

saponification

Answer Details

The boiling of fat and aqueous caustic soda is referred to as saponification. Saponification is the process of converting fat into soap through a reaction with an alkaline substance, such as caustic soda. The reaction results in the formation of soap (a salt of a fatty acid) and glycerol. This process is important in the manufacture of soap, as it allows the fat to be converted into a useful cleaning product.

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

Acids, Bases And Salts

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Question 20 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

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Question 21 Report

What is the concentration of a solution containing 2g of NaOH in 100cm3 of solution? [Na = 23, O =16, H = 1]

0.40 moldm

^{- 3}

0.50 moldm

^{- 3}

0.05 moldm

^{- 3}

0.30 moldm

^{- 3}

Answer Details

The concentration of a solution containing 2g of NaOH in 100cm3 of solution is 0.40 moldm-3. This can be calculated by using the formula: molarity (M) = number of moles of solute / volume of solution (in liters) First, we need to calculate the number of moles of NaOH in the solution. The molar mass of NaOH is (23 + 16 + 1) = 40 g/mol. So, 2g of NaOH is equal to 2/40 = 0.05 moles. Next, we need to convert the volume of the solution from cm3 to liters. 1 cm3 = 0.001 liters, so 100 cm3 = 0.1 liters. Finally, we can calculate the molarity as follows: M = 0.05 moles / 0.1 liters = 0.5 mol/L = 0.50 moldm-3 So, the concentration of the solution is 0.50 moldm-3.

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

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

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

Solubility Of Substances (Ghana Only)

Periodic Chemistry (Ghana Only)

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Question 22 Report

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)

Chemical Industry And Environment

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Question 23 Report

The general formula of alkanones is

RCHO

R

_{2}

CO

RCOOH

RCOOR

Chemistry Of Carbon Compounds (Nigeria Only)

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Question 24 Report

The lUPAC name for

1-methyl pentane

3-methylbutane

2-methylbutane

1-dimethyl propane

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Question 25 Report

The conductivity of an acid solution depends on the

amount of ions present and their mobilities

mobilities of the ions present

amount of ions present

temperature of the solution

Answer Details

The conductivity of an acid solution depends on the amount of ions present and their mobilities. When an acid dissolves in water, it forms ions that can carry an electric charge. These ions are what allows the solution to conduct electricity. The more ions there are in the solution, the better it can conduct electricity. However, not all ions have the same mobility or ability to move around in the solution. Ions with a higher mobility can move more easily through the solution, leading to a higher conductivity. Therefore, the conductivity of an acid solution is determined by both the amount of ions present and their mobilities. Other factors such as temperature can also affect conductivity, but the primary factors are the amount and mobility of ions.

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

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

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

Chemical Bonds (Ghana Only)

Periodic Chemistry (Ghana Only)

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Question 26 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 27 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 28 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)

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Question 29 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

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Question 30 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 31 Report

From the graph above, it may be concluded that

AgNO

_{3}

is probably not soluble at 1100

NaCl is insoluble in water

Pb(NO

_{3}

)

_{2}

is more soluble than KCIO

_{3}

The solubility of KCIO

_{3}

exceeds that of NaCl at all temperature

Solubility Of Substances (Ghana Only)

Solutions

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Question 32 Report

If the molecular mass of tetraoxosulphate (VI) acid is 98, calculate its vapour density

196

49

106

82

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Question 33 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)

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Question 34 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 35 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}

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Question 36 Report

The radio isotope used in industrial radiography for the rapid checking of faults in welds and casting is?

carbon-14

phosphorus-32

cobalt

iodine-131

Chemistry Of Carbon Compounds (Nigeria Only)

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Question 37 Report

The end products of burning a candle in the atmosphere are water and

carbon (II) oxide

sulphur (IV) oxide

carbon (IV) oxide

sulphur (VI) oxide

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Question 38 Report

What volume of oxygen will remain after reacting 8cm of hydrogen gas with 20cm of oxygen gas

10cm

^{3}

12cm

^{3}

14cm

^{3}

16cm

^{3}

Energy And Energy Changes

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Question 39 Report

According to Charles' law, the volume of a gas becomes zero at

0°C

-100°C

-273°C

-373°C

Answer Details

Charles' law states that the volume of a gas is directly proportional to its temperature, provided that the pressure remains constant. This means that as the temperature of a gas increases, its volume also increases. However, it is important to note that this law only applies to ideal gases, which are theoretical gases that perfectly follow the laws of thermodynamics. According to Charles' law, the volume of a gas becomes zero at absolute zero, which is approximately -273°C. At this temperature, the gas particles would have no kinetic energy and would be in their lowest energy state. The volume of a real gas would not actually become zero at absolute zero because the gas particles would have some residual intermolecular interactions that would prevent them from completely collapsing to a single point.

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

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Question 40 Report

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

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

Answer Details

Elements form bonds with other elements in order to attain a stable electron configuration, like the one found in noble gases. There are two types of bonds: covalent and ionic (also called electrovalent). In covalent bonds, two elements share electrons to attain a stable electron configuration. This type of bond is formed between two non-metal elements. In ionic bonds, one element donates electrons to another element, creating ions. This type of bond is formed between a metal and a non-metal element. Based on the information given, we can deduce the following: - P is a metal, as it has only 6 electrons. - Q is a non-Metal, as it has 11 electrons. - R is a metal, as it has 15 electrons. - S is a non-Metal, as it has 17 electrons. So, from this information, we can conclude that: - P will form an ionic bond with R, as P is a metal and R is a metal. - Q will form a covalent bond with S, as Q is a non-Metal and S is a non-Metal. Therefore, the correct answer is "Q will form a covalent bond with S."

Read lesson note on Atomic Structure And Bonding (JAMB)