JAMB UTME - Chemistry - 2009 | Green Bridge CBT

Question 1 Report

Which of the following metals is purified commercially by electrolysis?

Cu Correct answer

Answer Details

Read lesson note on Electrolysis (JAMB)

Electrolysis

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Question 2 Report

C(s) + H2O(g) → H2(g) + CO2(g)

ΔG for the reaction above at 1300k is -43KJ. At this temperature, the reaction is

not feasible

at equilibrium

feasible Correct answer

exothermic

Answer Details

At 1300K, the value of ΔG for the given reaction is negative (-43KJ), indicating that the reaction is feasible. A negative ΔG value implies that the products are more stable than the reactants, and the reaction will proceed spontaneously in the forward direction. The fact that ΔG is negative also means that the reaction is exothermic, releasing energy to the surroundings. Therefore, the correct answers are: feasible and exothermic.

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

Kinetic Theory Of Matter And Gas Laws

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Question 3 Report

The oxidation of ammonia in excess air produces

NO Correct answer

N2O

NO2

N2O4

Answer Details

Read lesson note on Oxidation And Reduction (JAMB)

Oxidation And Reduction

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Question 4 Report

The percentage of water of crystallization in ZnSO4.7H2O is

[Zn = 65, S = 32, O = 1, H = 1]

33%

44%
Correct answer

55%

87%

Answer Details

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

Kinetic Theory Of Matter And Gas Laws

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Question 5 Report

The acid used in electrolysis of water is dilute

HNO3

CH3COOH

H2SO4 Correct answer

HCl

Answer Details

The acid used in the electrolysis of water is dilute sulfuric acid, which is represented by the formula H2SO4.

Read lesson note on Electrolysis (JAMB)

Electrolysis

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Question 6 Report

The oxidation state of Cr in K2Cr2O7 is

+6 Correct answer

Answer Details

The oxidation state of an element refers to the number of electrons it loses, gains, or shares when it forms a compound. In the given compound, K2Cr2O7, the total oxidation state of potassium (K) is +2 (since there are two K atoms and each contributes +1), and the total oxidation state of oxygen (O) is -2 (since there are seven O atoms and each contributes -2). The compound is neutral, which means the sum of all the oxidation states must be zero. Therefore, we can use this information to find the oxidation state of chromium (Cr). Let x be the oxidation state of Cr. Then, (+2) + 2x + (-2)(7) = 0 Simplifying: 2x - 12 = 0 2x = 12 x = 6 Therefore, the oxidation state of Cr in K2Cr2O7 is +6. So the correct option is +6.

Read lesson note on Oxidation And Reduction (JAMB)

Oxidation And Reduction

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Question 7 Report

Which of the following molecules has two other positional isomers?

CH3CH2Br

CH3CHBrCH3

CBr2F2

CH2CHBrCH2Br Correct answer

Answer Details

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

Chemistry Of Carbon Compounds (Nigeria Only)

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Question 8 Report

The major source of oxides of nitrogen is from the burning of

coal

wood

fuel Correct answer

chlrofluorocarbons

Answer Details

Nitrogen oxides form when fuel is burned at high temperatures

Read lesson note on Environmental Pollution (JAMB)

Environmental Pollution

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Question 9 Report

If 10.5g of lead (II) trioxonitrate (V) is dissolved in 20cm3 of distilled water at 18oC, the solubility of the solute in mol dm-3 is

[Pb = 207, N = 14, O = 16]

1.60 Correct answer

5.25

16.00

525.00

Answer Details

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

Kinetic Theory Of Matter And Gas Laws

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Question 10 Report

The type of iron that is best suited for welding, making nails, chains and iron rods is

pig iron

wrought iron Correct answer

cast iron

iron pyrites

Answer Details

The type of iron that is best suited for welding, making nails, chains, and iron rods is wrought iron. Wrought iron is a soft, malleable, and ductile form of iron that contains very low carbon content. Its low carbon content makes it easier to shape and weld without becoming brittle, which is why it's often used in construction applications where high strength is required. In contrast, pig iron, cast iron, and iron pyrites are not suitable for these applications due to their higher carbon content and brittleness.

Read lesson note on Metals And Their Compounds (JAMB)

Metals And Their Compounds

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Question 11 Report

Cathode rays causes an object placed behind a perforated anode to cast a shadow on the screen. This observation shows that the rays

are positively charged

are negatively charged

have mass

travel in straight lines Correct answer

Answer Details

When cathode rays pass through a perforated anode, they cast a shadow of the object placed behind the anode on the screen. This happens because cathode rays are negatively charged particles and travel in straight lines. Therefore, they are blocked by the solid object (perforated anode) and form a shadow on the screen where they do not pass through. This observation rules out the possibility that cathode rays are positively charged or have mass, and indicates that they are negatively charged particles that travel in straight lines.

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

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

Structure Of The Atom (Ghana Only)

Kinetic Theory Of Matter And Gas Laws

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Question 12 Report

The molecular formula of a common organic laboratory anaesthetic is

CHCl3 Correct answer

CHI3

CCl4

CHF3

Answer Details

The question is asking for the molecular formula of a common organic laboratory anaesthetic. To answer this question, we need to look at the options provided. Among the options, we see four different molecular formulas, each with a different combination of atoms. We need to identify which of these is the correct molecular formula for a common organic laboratory anaesthetic. Out of the four options, the molecular formula that corresponds to a common organic laboratory anaesthetic is CHCl₃ (option A). This is the formula for chloroform, which is a commonly used anaesthetic in laboratories. Therefore, the correct answer to this question is option A: CHCl₃.

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

Chemistry Of Carbon Compounds (Nigeria Only)

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Question 13 Report

A compound commonly used for sterilization and preservation of specimens and food is

ethanol Correct answer

benzene

ether

ammonia

Answer Details

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Question 14 Report

In the electrolytic extraction of aluminum, the function of the molten cryolite is to

precipitate aluminium hdroxide

lower the melting point of aluminium oxide Correct answer

act as a raw materials

act as a solvent

Answer Details

Read lesson note on Electrolysis (JAMB)

Electrolysis

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Question 15 Report

The basic assumption in the kinetic theory of gases that the collisions of the gaseous molecules are perfectly elastic implies that the

forces of attraction and repulsion are in equilibrium

gaseous molecules can occupy any available space

gaseous molecules will continue their motion indefinitely Correct answer

gases can be compressed

Answer Details

The basic assumption in the kinetic theory of gases that the collisions of the gaseous molecules are perfectly elastic implies that gaseous molecules will continue their motion indefinitely. When the collisions are perfectly elastic, the gaseous molecules transfer energy without losing any energy themselves, which means that their motion will continue indefinitely unless interrupted by a collision with another molecule or a wall. This is the reason gases have the ability to expand and occupy any available space.

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

Kinetic Theory Of Matter And Gas Laws

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Question 16 Report

A mixture of sugar and sulphur can be separated by

dissolution in water, evapouration and filtration

filtration, evaporation and dissolution in water

dissolution in water, filtration and evaporation Correct answer

evaporation, dissolution in water and filtration

Answer Details

The mixture of sugar and sulfur can be separated by dissolution in water, filtration and evaporation. First, the mixture can be dissolved in water to dissolve the sugar. Then, the resulting solution can be filtered to remove the undissolved sulfur. Finally, the water can be evaporated from the sugar solution to obtain the pure sugar. Therefore, option (C) is the correct answer.

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 17 Report

CuO(s) + H2(g) ↔ Cu(s) + H2O(l)

What is the effect of increasing the pressure on the equilibrium reaction above?

The equilibrium is shifted to the left

The equilibrium is shifted to the right

There is no effect Correct answer

More H2(g) is produced

Answer Details

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

Read lesson note on Chemical Kinetics And Equilibrium Systems (Ghana Only) (WAEC)

Read lesson note on Chemical Equilibria (JAMB)

Chemistry Of Carbon Compounds (Nigeria Only)

Chemical Kinetics And Equilibrium Systems (Ghana Only)

Chemical Equilibria

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Question 18 Report

Which of the following allotrope of carbon is a constituent of a lead pencil?

Graphite Correct answer

Diamond

Lampblack

Soot

Answer Details

The answer to this question is Graphite. Graphite is a soft, black, lustrous form of carbon that is a good conductor of electricity.

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

Chemistry Of Carbon Compounds (Nigeria Only)

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Question 19 Report

Water can be obtained as the only product during

combustion of hydrocarbons

neutralization of an acid by base

combustion of hydrogen Correct answer

electrolysis of brine

boiling water

Answer Details

Read lesson note on Water (JAMB)

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

Water

Acids, Bases And Salts (Ghana Only)

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Question 20 Report

A catalyst increase the rate of a chemical reaction by providing a path that

raise the activiation energy

increase the temperature

lowers the activation energy Correct answer

increase the concentration

Answer Details

A catalyst increases the rate of a chemical reaction by providing an alternative pathway that lowers the activation energy required for the reaction to occur. This lower activation energy makes it easier for the reactants to form products, which in turn speeds up the reaction. Therefore, the correct option is "lowers the activation energy".

Read lesson note on Rates Of Chemical Reaction (JAMB)

Rates Of Chemical Reaction

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Question 21 Report

0.0075 mole of calcium trioxocarbonate (IV) is added to 0.015 mole of a solution of hydrochloric acid. The volume of gas evolved at s.t.p is

[Molar volume of a gas at s.t.p = 22.4 dm3]

224cm3

168cm3 Correct answer

112cm3

100cm3

Answer Details

Read lesson note on Stoichiometry And Chemical Reactions (WAEC)

Stoichiometry And Chemical Reactions

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Question 22 Report

Copper metal dissolves in concentrated trioxonitrate (V) acid with the resultant evolution of

CO2

SO2

NO2 Correct answer

Answer Details

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

Acids, Bases And Salts

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Question 23 Report

The mixture of gases used in a photographer's flash tube is

argon and krypton

krypton and xenon Correct answer

helium and argon

argon and xenon

Answer Details

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

Kinetic Theory Of Matter And Gas Laws

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Question 24 Report

A cracking process in petroleum refining can be represented by

heptane to heptene

heptane to 3-methylhexane

heptane to propene and butane Correct answer

heptane to 2,3,3-trimethybutane

Answer Details

Cracking is a process used in petroleum refining to break down large hydrocarbon molecules into smaller, more useful molecules. The cracking of heptane, a hydrocarbon with 7 carbon atoms, can result in the formation of various smaller molecules. Among the given options, the cracking of heptane to propene and butane is the representation of the process. Propene and butane are smaller, more useful molecules that can be used for various purposes, such as fuel and chemical feedstocks.

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

Chemistry Of Carbon Compounds (Nigeria Only)

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Question 25 Report

Which quantum number divides shells into orbitals?

principal

Arzimuthal Correct answer

Magnetic

Spin

Answer Details

The quantum number that divides shells into orbitals is the azimuthal quantum number. This number determines the shape of the orbital and can have values ranging from 0 to n-1, where n is the principal quantum number. Each value of the azimuthal quantum number corresponds to a different subshell, which in turn determines the shape of the orbital. For example, an azimuthal quantum number of 0 corresponds to an s subshell, which has a spherical shape, while an azimuthal quantum number of 1 corresponds to a p subshell, which has a dumbbell shape with two lobes. So, the azimuthal quantum number plays a crucial role in dividing shells into orbitals.

Read lesson note on Atomic Structure And Bonding (JAMB)

Atomic Structure And Bonding

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Question 26 Report

What current will deposit 3.25g of zinc in 2hrs?

[Zn = 65, F = 96500 mol-]

3.25A

2.00A

1.34A Correct answer

0.67A

Answer Details

To find the current required to deposit 3.25g of zinc in 2 hours, we need to use Faraday's laws of electrolysis which states that the mass of substance deposited during electrolysis is directly proportional to the quantity of electricity passed through it. We can use the formula: Mass of substance = (Current × Time × Atomic weight) / (96500 × Valency) where the atomic weight and valency are taken from the chemical formula of the substance. For zinc, the atomic weight is 65 and the valency is 2. Plugging in the values given in the question, we get: 3.25 = (Current × 2 × 65) / (96500 × 2) Solving for the current, we get: Current = (3.25 × 96500 × 2) / (2 × 65 × 2) = 1340.38 A Rounding off to two significant figures, the answer is 1.3A. Therefore, the answer is: 1.34A.

Read lesson note on Electrolysis (JAMB)

Electrolysis

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Question 27 Report

One of the products of the thermal decomposition of sodium trioxonitrate (V) is

sodium

nitrogen

sodium dioxonitrate (III) Correct answer

sodium oxide

Answer Details

Read lesson note on Chemical Combination (JAMB)

Chemical Combination

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Question 28 Report

For a given solute, the concentration of its saturated solution in different solvents are

the same at the same temperature

different at the same temperature Correct answer

the same at different temperature

constant

Answer Details

Read lesson note on Solubility (JAMB)

Solubility

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Question 29 Report

An organic compound reacted with bromine water to give a colourless solution. The compound is probably an

alkene

alkanal

alkyne Correct answer

alkanone

Answer Details

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Question 30 Report

Which of the following class of compounds can exist as dipolar ions in solution?

Alkanoic acid

Fatty acids

Dialkanoic acids

Amino acids Correct answer

Answer Details

A class of compounds that can exist as dipolar ions in solution are those that contain functional groups with both a positive and a negative charge. These are called zwitterions. Amino acids are an example of a compound that can exist as a dipolar ion in solution, as they contain both an amino group (NH2) with a positive charge and a carboxyl group (COOH) with a negative charge. Therefore, the answer is: Amino acids.

Read lesson note on Basic Biochemistry And Synthetic Polymers (WAEC)

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

Basic Biochemistry And Synthetic Polymers

Periodic Chemistry (Ghana Only)

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Question 31 Report

The salt formed from a reaction between citric acid and sodium hydroxide in solution will be

acidic

basic Correct answer

complex

neutral

Answer Details

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

Acids, Bases And Salts

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Question 32 Report

A gas exerts pressure on its container because

the molecules of a gas collide with the walls of the container Correct answer

some of the molecules are moving faster than others

of the collisions of the molecules with each other

of the mass of the molecules of the gas

Answer Details

The reason a gas exerts pressure on its container is that the molecules of the gas collide with the walls of the container. When gas molecules are moving around, they hit the walls of their container, which creates a force on the walls, and this force per unit area is defined as pressure. The more molecules there are in the container, the more collisions there will be, and therefore the greater the pressure exerted by the gas. So, the correct option is "the molecules of a gas collide with the walls of the container".

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

Kinetic Theory Of Matter And Gas Laws

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Question 33 Report

The gasification of coke is used for the manufacture of

producer gas Correct answer

natural gas

synthetic gas

industrial gas

artificial gas

Answer Details

The gasification of coke is used for the manufacture of producer gas. Producer gas is a mixture of carbon monoxide and hydrogen that is produced by the partial combustion of a carbon-based fuel such as coke. This gas is used as a fuel in various industrial processes, including in the production of chemicals and as a fuel for heat and power generation. The gasification process involves heating the coke to high temperatures in the presence of a limited amount of oxygen to produce the desired gas mixture.

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

Kinetic Theory Of Matter And Gas Laws

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Question 34 Report

Organic molecules that have the suffix-ene are unsaturated hydrocarbons that have

a single bond

a double bond Correct answer

a triple bond

an ionic bond

Answer Details

Organic molecules with the suffix -ene are unsaturated hydrocarbons that have a double bond between two of their carbon atoms. This means that each carbon atom is bonded to two other atoms instead of four, which results in the molecule having fewer hydrogen atoms than a saturated hydrocarbon with the same number of carbon atoms. The double bond between the carbon atoms is what distinguishes -ene molecules from saturated hydrocarbons that have only single bonds. Therefore, the correct answer is: "a double bond".

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Question 35 Report

In the diagram above, which of the curves represents the evolution of oxygen with time in the equation 2KClO3(s) → 2KCl(s) + 3O2(g)?

Z Correct answer

Answer Details

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

Kinetic Theory Of Matter And Gas Laws

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Question 36 Report

If an atom is represented as \( {}^{23}_{11}X \), which of the following deduction is correct?

it contains 12 protonic

it forms a covalent chloride

its atomic number is 23

it is an alkali metal Correct answer

Answer Details

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Question 37 Report

The type of bonding in {Cu(NH3)4}2+ is

coordinate Correct answer

electrovalent

metallic

covalent

Answer Details

The type of bonding in {Cu(NH3)4}2+ is coordinate. In this type of bonding, one atom donates a pair of electrons to another atom or ion. In this case, the nitrogen atoms in the ammonia molecules donate a lone pair of electrons to the copper ion, forming a coordinate covalent bond.

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

Read lesson note on Atomic Structure And Bonding (JAMB)

Chemical Bonds (Ghana Only)

Atomic Structure And Bonding

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Question 38 Report

The equilibrium of an endothermic reaction which proceeds with an increase in volume can be shifted in the reverse direction by

increasing the temperature and decreasing the pressure

increasing the pressure and increasing the temperature

decreasing the temperature and increasing the pressure Correct answer

decreasing the pressure and decreasing the temperature

Answer Details

When an endothermic reaction takes place, an increase in temperature will shift the equilibrium towards the products side. Similarly, increasing the pressure will shift the equilibrium towards the side with fewer gas molecules. Since an increase in volume indicates more gas molecules on the product side, decreasing the volume will shift the equilibrium towards the products. Therefore, decreasing the pressure (increasing the volume) will shift the equilibrium towards the reactants side. Decreasing the temperature will also shift the equilibrium towards the reactants side. So, the correct option is decreasing the temperature and increasing the pressure.

Read lesson note on Chemical Equilibria (JAMB)

Chemical Equilibria

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Question 39 Report

Which of the following hydrocarbons is mainly used as fuel?

Methylene

Ethylene

Methane Correct answer

Ethyne

Answer Details

Among the given options, the hydrocarbon mainly used as fuel is methane. Methane is a simple hydrocarbon with a chemical formula of CH4. It is a major component of natural gas and is also produced by many industrial processes. Methane is used as fuel for heating and cooking purposes in households and for power generation in industries. Therefore, the correct option is "Methane."

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

Chemistry Of Carbon Compounds (Nigeria Only)

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Question 40 Report

When sodium trioxocarbonate (IV) decahydrate loses its water of crystallization to the atmosphere, the process is

deliquescence

efflorescence Correct answer

hygroscopic

effervesecence

Answer Details

When sodium trioxocarbonate (IV) decahydrate loses its water of crystallization to the atmosphere, the process is called efflorescence. This is a process by which a hydrated compound loses its water of crystallization, usually due to exposure to air, resulting in a dry, powdery substance. In this case, sodium trioxocarbonate (IV) decahydrate, also known as washing soda, loses its ten molecules of water of crystallization to the atmosphere, resulting in the formation of anhydrous sodium carbonate.

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

Acids, Bases And Salts

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Question 41 Report

What volume of 1.5M solution of KOH would contain 0.045 moles

67.50 cm3

30.00 cm3 Correct answer

6.75 cm3

3.00 cm3

Answer Details

To determine the volume of 1.5M solution of KOH that contains 0.045 moles, we need to use the formula: moles = concentration x volume Rearranging this formula to solve for volume gives: volume = moles / concentration Substituting the given values, we have: volume = 0.045 moles / 1.5 M = 0.03 L Converting this to cubic centimeters (cm³) by multiplying by 1000 gives: volume = 0.03 L x 1000 cm³/L = 30 cm³ Therefore, the answer is 30.00 cm³.

Read lesson note on Stoichiometry And Chemical Reactions (WAEC)

Stoichiometry And Chemical Reactions

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Question 42 Report

The simplest branched-chain hydrocarbon is

ethane

ethene

propane

butane Correct answer

Answer Details

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

Chemistry Of Carbon Compounds (Nigeria Only)

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Question 43 Report

Two equal bulbs, one containing ammonia and the other nitrogen are opened mouth-to-mouth to each other at room temperature. The entropy in the mixture of gases is likely to

remain unchanged

increase Correct answer

decrease

change

Answer Details

When the two bulbs are opened mouth-to-mouth, the ammonia and nitrogen gases will mix together to form a homogeneous mixture. This process increases the disorder or randomness of the system, which is measured by entropy. Therefore, the entropy of the mixture of gases is likely to increase. Thus, the correct option is "increase".

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

Read lesson note on Chemical Kinetics And Equilibrium Systems (Ghana Only) (WAEC)

Kinetic Theory Of Matter And Gas Laws

Chemical Kinetics And Equilibrium Systems (Ghana Only)

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Question 44 Report

which of the following metals will show the highest metallic character?

Zinc

Copper

Barium

Calcium Correct answer

Answer Details

Read lesson note on Metals And Their Compounds (JAMB)

Metals And Their Compounds

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Question 45 Report

Which of the following is a physical change?

Freezing ice cream Correct answer

dissolving calcium in water

burning kerosene

Exposing white phosphorus to air

Answer Details

A physical change is a type of change that occurs in the physical properties of a substance, such as size, shape, state, or phase, without altering its chemical composition. Therefore, to determine which option is a physical change, we need to consider whether the process described involves a change in the physical properties of the substance or not. - Freezing ice cream: This involves a change in state from liquid to solid without changing the chemical composition of the ice cream, so it is a physical change. - Dissolving calcium in water: This is a process that involves a chemical change since it results in the formation of calcium ions and hydroxide ions in the water. - Burning kerosene: This is a chemical change since it involves the combustion of kerosene to produce carbon dioxide and water vapor. - Exposing white phosphorus to air: This is a chemical change since it involves the reaction of white phosphorus with oxygen in the air to form a new substance, phosphorus oxide. Therefore, the only option that describes a physical change is "Freezing ice cream".

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 States Of Matter (WAEC)

Solubility Of Substances (Ghana Only)

Kinetic Theory Of Matter And Gas Laws

States Of Matter

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Question 46 Report

Lucas reagent is used to test for

alkanes

alkanoic acids

alkanols Correct answer

amines

Answer Details

Lucas reagent is used to test for the presence of primary, secondary, and tertiary alcohols. The reagent contains zinc chloride in concentrated hydrochloric acid, which reacts with the alcohol to form an alkyl chloride. The reaction rate depends on the type of alcohol: primary alcohols react slowly, secondary alcohols react more quickly, and tertiary alcohols react almost immediately. Therefore, the correct answer to the question is "alkanols."

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

Periodic Chemistry (Ghana Only)

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Question 47 Report

If the relative molecular mass of an element is not a whole number, it can be deduced that the element is

naturally radioactive

abundant in nature

a transition metal

an isotopic mixture Correct answer

Answer Details

If the relative molecular mass of an element is not a whole number, it can be deduced that the element is an isotopic mixture. Isotopes are atoms of the same element that have different numbers of neutrons, which can result in a different relative atomic mass. When an element has isotopes with different masses, the relative molecular mass will not be a whole number. For example, carbon has two stable isotopes, carbon-12 and carbon-13, which means that naturally occurring carbon is an isotopic mixture and has a relative molecular mass that is not a whole number (12.01). Therefore, option D is the correct answer.

Read lesson note on Atomic Structure And Bonding (JAMB)

Atomic Structure And Bonding

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Question 48 Report

Hydrogen sulphide gas can act as

an oxidizing agent

a dehydrating agent

a bleaching agent

a precipitating agent Correct answer

Answer Details

Read lesson note on Oxidation And Reduction (JAMB)

Oxidation And Reduction

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Question 49 Report

The colour changes observed when testing for reducing agents using acidified potassium heptaoxodichromate (IV) solution is

yellow to purple

orange to green Correct answer

green to orange

purple to yellow

Answer Details

Acidified potassium heptaoxodichromate (IV) solution is a commonly used oxidizing agent. When it is added to a reducing agent, the reducing agent is oxidized, and the color of the solution changes. In the case of acidified potassium heptaoxodichromate (IV) solution, the initial color is orange. As the reducing agent reduces the potassium heptaoxodichromate (IV) to potassium heptaoxodichromate (III), the orange color disappears, and the solution turns green. The intensity of the green color can vary depending on the concentration of the reduced potassium heptaoxodichromate (III). Therefore, the correct answer is "orange to green."

Read lesson note on Oxidation And Reduction (JAMB)

Oxidation And Reduction

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Question 50 Report

The gas that is most useful in protecting humans against solar radiation is

chlorine

ozone Correct answer

carbon (IV) oxide

hydrogen sulphide

Answer Details

The gas that is most useful in protecting humans against solar radiation is ozone. Ozone is a molecule made up of three oxygen atoms and is present in the earth's atmosphere, where it forms a protective layer known as the ozone layer. This layer helps to block harmful ultraviolet (UV) radiation from the sun, which can cause skin cancer, cataracts, and other health problems in humans. Chlorine, carbon (IV) oxide, and hydrogen sulphide are not known to be useful in protecting humans against solar radiation.

Read lesson note on Air (JAMB)

Air

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