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

the litmus turns red and oxygen is evolved

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

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?

Filtration followed by distillation

Neutralization with sodium hydroxide followed by distillation

Neutralization with sodium hydroxide followed by filtration

2KClO3(g) MNO3? 2KCl(s) + 3O2(g) The importance of the catalyst in the reaction above is that

the reaction takes place more rapidly at a lower temperature

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

Beryllium and Aluminium have similar properties because they

are positioned diagonally to each other

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

(I). 3CuO(s) + 2NH3(g) -----> 3Cu(s) + 3H2O(l) + N2(g) (II). 2NH3(g) + 3Cl2(g) -----> 6HCl(g) + N2(g) (III). 4NH3(g) + 3O2(g) -----> 6H2O(l) + N2(g) The reactions represented by the equations above demonstrate the

oxidizing properties of ammonia

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)

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

separating a mixture by distillation

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

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

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

Which of the following pairs of substances will react further with oxygen to form a higher oxide?

CO

_{2}

and H

_{2}

O

NO and H

_{2}

O

CO and CO

_{2}

SO

_{2}

and NO

Oxidation And Reduction

Separation Of Mixtures And Purification Of Chemical Substances

View Answer

Question 2 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 3 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 4 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 5 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 6 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 7 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)

Kinetic Theory Of Matter And Gas Laws

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Question 8 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 9 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 10 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 11 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)

Kinetic Theory Of Matter And Gas Laws

Periodic Chemistry (Ghana Only)

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Question 12 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 13 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 14 Report

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

strength of the core

position of the metal in the electrochemical series

source of the core

position of the metal in the periodic table

Answer Details

The choice of method for extracting a metal from its ores depends on the position of the metal in the electrochemical series. The electrochemical series is a list of metals arranged in order of their ability to gain or lose electrons. The metals at the top of the series (such as sodium and potassium) are very reactive and will readily lose electrons, while those at the bottom (such as gold and platinum) are less reactive and less likely to lose electrons. The position of a metal in the electrochemical series determines the method of extraction that should be used. For example, metals at the top of the series are usually extracted by electrolysis, which involves passing an electric current through a molten compound of the metal. This process is necessary because the metals at the top of the series are very reactive and are strongly bonded to other elements in their ores. On the other hand, metals at the bottom of the series are usually extracted by reduction with carbon or hydrogen. This is because these metals are less reactive and can be separated from their ores by reacting them with a reducing agent that can take away the oxygen and other impurities. Therefore, the position of the metal in the electrochemical series is a crucial factor in determining the method of extraction that should be used to extract it from its ores.

Read lesson note on Chemical Equilibria (JAMB)

Chemical Equilibria

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Question 15 Report

To what volume must \(300\text{cm}^3\) of 0.60M sodium hydroxide solution be diluted to give a 0.40M solution?

450cm

^{3}

300cm

^{3}

200cm

^{3}

150cm

^{3}

Kinetic Theory Of Matter And Gas Laws

SOLUBILITY OF SUBSTANCES (Nigeria Only)

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Question 16 Report

The Consecutive members of an alkane homologous series differ by

CH

_{2}

CH

_{3}

C

_{n}

H

_{n}

Answer Details

The consecutive members of an alkane homologous series differ by a CH2 unit. This means that each successive member of the alkane series has one more CH2 unit than the previous member. For example, consider the simplest alkane, methane (CH4). The next member of the series is ethane (C2H6), which differs from methane by one CH2 unit. The next member after that is propane (C3H8), which differs from ethane by another CH2 unit. This pattern continues for all members of the alkane homologous series. The reason for this is that each carbon atom in the alkane chain must be bonded to four other atoms, which are usually hydrogen atoms. This means that each carbon atom in the chain can only bond to one other carbon atom. Therefore, the length of the alkane chain can only increase by adding CH2 units to the end of the chain. In summary, the consecutive members of an alkane homologous series differ by a CH2 unit because this is the only way to add length to the alkane chain while maintaining the required number of bonds for each carbon atom in the chain.

Read lesson note on Chemical Equilibria (JAMB)

Chemical Equilibria

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Question 17 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

View Answer

Question 18 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 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

Sieving is a technique used to separate mixtures containing solid particles of

small sizes

large sizes

different sizes

the same size

Answer Details

Sieving is a technique used to separate mixtures containing solid particles of different sizes. A sieve is a mesh or perforated screen that is used to separate particles based on their size. The mixture is poured onto the sieve, and the particles that are too large to pass through the holes are left on top, while the smaller particles fall through the holes and are collected below. This process allows for the separation of the different-sized particles, making it easier to purify or further process the mixture.

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 21 Report

ME + nF -----> pG + qH

In the equation shown, the equilibrium constant is given by?

\frac{[E]^{m} [F]}{[G]^{p} [H]^{q}}

\frac{[E] [F]}{[G] [H]}

\frac{[G]^{p} [H]^{p}}{[E]^{m} [F]^{n}}

\frac{[G] [H]}{[E] [F]}

Answer Details

The equilibrium constant for a chemical reaction is a measure of the balance between the reactants and products of a reaction at a particular temperature. The equilibrium constant is given by the ratio of the product of the concentration of the products raised to their stoichiometric coefficients, to the product of the concentration of the reactants raised to their stoichiometric coefficients. In the equation ME + nF -> pG + qH, the correct expression for the equilibrium constant is [G]^p * [H]^q / [E]^m * [F]^n, represented by.

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

Read lesson note on Structure Of The Atom (WAEC)

Chemical Kinetics And Equilibrium Systems (Ghana Only)

Structure Of The Atom

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Question 22 Report

The type of bonding in \(\left[\mathrm{Cu}(\mathrm{NH}_3)_4\right]^{2+}\) is

coordinate

electrovalent

metallic

covalent

Answer Details

The type of bonding in [Cu(NH3)4]2+ is coordinate bonding. Coordinate bonding (also known as dative covalent bonding) is a type of covalent bonding where one atom (in this case, the nitrogen atom in NH3) donates a pair of electrons to another atom or ion (in this case, the copper ion Cu2+). The donating atom is called the ligand, and the receiving atom or ion is called the central metal ion. In [Cu(NH3)4]2+, each ammonia molecule (NH3) donates a lone pair of electrons on the nitrogen atom to the copper ion, forming four coordinate bonds between the ligands and the central copper ion. The presence of coordinate bonds is indicated by the use of square brackets around the coordination compound, and the charge on the compound is indicated by the superscript outside the brackets. Therefore, the answer is option A: coordinate.

View Answer

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

In the reaction between sodium hydroxide and sulphuric acid solutions, what volume of 0.5 molar sodium hydroxide would exactly neutralise 10cm3 of 1.25 molar sulphuric acid?

5cm

^{3}

10cm

^{3}

20cm

^{3}

50cm

^{3}

Stoichiometry And Chemical Reactions

View Answer

Question 25 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 26 Report

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

decreasing

increasing

constant

neutral

View Answer

Question 27 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)

Acids, Bases And Salts (Ghana Only)

Periodic Chemistry (Ghana Only)

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Question 28 Report

Which of the following statements is correct about the periodic table?

Elements in the same period have the same number of valence electrons

The valence electrons of the elements in the same period increase progressively across the period

Elements in the same group have the same number of electron shells

The non-metallic Properties of the elements tend to decrease across each period

Atomic Structure And Bonding

View Answer

Question 29 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 30 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 31 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 32 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 33 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 34 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

Kinetic Theory Of Matter And Gas Laws

View Answer

Question 35 Report

Which of the following separation techniques can be employed in obtaining solvent from its solution?

Evaporation

Distillation

Filtration

Precipitation

Answer Details

The separation technique that can be employed in obtaining a solvent from its solution is evaporation. Evaporation is a process that involves heating a solution to vaporize the solvent, leaving behind the solute. The vaporized solvent can then be condensed and collected as a pure liquid. This technique is commonly used in industry and laboratory settings to recover solvents from solutions, as it is a simple and effective way to purify liquids. Distillation can also be used to separate a solvent from a solution, but it is a more complex process that involves boiling the solution and then condensing the vapors in a separate apparatus. Filtration and precipitation are not suitable for separating a solvent from a solution, as they are primarily used to separate solid particles from a liquid mixture.

Read lesson note on Solubility (JAMB)

Solubility

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Question 36 Report

Calculate the pH of \(0.05\ \mathrm{mol\,dm^{-3}}\ \mathrm{H_2SO_4}\)

1.30

1.12

1.00

0.30

Answer Details

To solve this problem, we need to use the formula for calculating the pH of a solution, which is: pH = -log[H+] where [H+] is the concentration of hydrogen ions in moles per liter. The given chemical equation is: H2SO4 + 2H2O → 2H3O+ + SO42- From this equation, we can see that one molecule of sulfuric acid (H2SO4) can donate two hydrogen ions (H+) to the solution, which means that the concentration of hydrogen ions is twice the concentration of sulfuric acid. Therefore, the concentration of hydrogen ions in this solution is: [H+] = 2 x 0.05 moldm^-3 = 0.1 moldm^-3 Now we can use the formula for pH: pH = -log[H+] pH = -log(0.1) pH = 1.00 Therefore, the pH of the solution is 1.00.

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

Periodic Chemistry (Ghana Only)

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Question 37 Report

When air which contains the gases Oxygen, nitrogen, carbondioxide, water vapour and the rare gases, is passed through alkaline pyrogallol and then over quicklime, the only gases left are;

nitrogen and carbondioxide

the rare gases

nitrogen and oxygen

nitrogen and the rare gases

Air

View Answer

Question 38 Report

The collision theory explains reaction rates in terms of

size of the product

frequency of collision of the reactants

size of reactant

frequency of collision of the products

Answer Details

The collision theory explains reaction rates in terms of the frequency of collision of the reactants. In other words, the theory suggests that for a chemical reaction to occur, the reactant particles must collide with sufficient energy and with the correct orientation. The frequency of these collisions is an important factor in determining the rate of the reaction. The more frequently the reactant particles collide, the more likely it is that they will react and form products. Therefore, increasing the frequency of collisions between reactant particles can increase the rate of a chemical reaction. The size of the reactants or the products does not play a significant role in the collision theory.

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

Kinetic Theory Of Matter And Gas Laws

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Question 39 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 40 Report

Which of the following is used to power steam engines?

lubricating oil

coal

bitumen

diesel oil

Answer Details

Coal is the fuel that is typically used to power steam engines. Coal is burned in a furnace to heat water and produce steam, which is then used to power a steam engine. The steam engine converts the energy from the steam into mechanical energy, which can be used to power machines or generate electricity. Coal is a fossil fuel that has been used for centuries as a source of energy, and it played a significant role in the industrial revolution, powering steam engines that were used to drive machines in factories and transport goods and people by train. Today, steam engines are less common as other forms of energy have taken their place, but they remain an important part of our history and technological development.

Read lesson note on Solubility (JAMB)

Solubility

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