Chemistry 2022

Objective Questions

The by-product of fermentation of sugar is

A) Carbon (IV) oxide B) Ethanoic acid C) Propanol D) Propan-1,2,3-triol

Correct Answer: A) Carbon (IV) oxide

Which of the following sugars is a product of the condensation of monosaccharides?

A) Galactose B) Maltose C) Glucose D) Fructose

Correct Answer: B) Maltose

The cleansing effect of soap is low in acidic water because of

A) The formation of unionized fatty acid B) Increase in the pH of the soap molecules C) Anti-biodegradable effect of hydrogen ions D) The hardness of the acidic water

Correct Answer: A) The formation of unionized fatty acid

The following compounds are condensation polymers except

A) Nylon B) Protein C) Starch D) Polyethene

Correct Answer: D) Polyethene

What amount of electricity is required to deposit one mole of aluminium from a solution of AlCl₃?

A) One faraday B) One ampere C) Three faradays D) Three amperes

Correct Answer: C) Three faradays

Which of the following compounds would react rapidly with bromine?

A) Benzene B) Hexane C) Hexene D) Hexanol

Correct Answer: C) Hexene

Alkanols can be manufactured from alkenes by the initial reaction of alkenes with

A) Bromine in tetrachloromethane B) Concentrated tetraoxosulphate (VI) acid C) Aqueous potassium tetraoxomanganate (VII) D) Sodium hydroxide solution

Correct Answer: B) Concentrated tetraoxosulphate (VI) acid

Which of the following statements about the standard hydrogen electrode is not correct?

A) The hydrogen gas is at a pressure of 1 atmosphere B) A solution containing 1 mol dm⁻³ of H⁺(aq) ions is used C) A platinum electrode is used D) The temperature is kept at 20 °C

Correct Answer: D) The temperature is kept at 20 °C

If 60 g of M combines with 24 g of oxygen, what would the empirical formula of the oxide be?
(Molar mass of M = 120, O = 16)

A) MO B) MO₂ C) MO₃ D) MO₄

Correct Answer: D) MO₄

The products of the electrolysis of dilute sodium chloride using carbon electrodes are

A) Chlorine and sodium B) Oxygen and hydrogen C) Chlorine and hydrogen D) Hydrogen and oxygen

Correct Answer: C) Chlorine and hydrogen

Determine the quantity of electricity used when a current of 0.20 amperes is passed through an electrolytic cell for 60 minutes.

A) 12 C B) 120 C C) 360 C D) 720 C

Correct Answer: D) 720 C

Oxochlorate(I) acid is used as a bleaching agent because it is

A) A weak acid B) A reducing agent C) An oxidizing agent D) A strong acid

Correct Answer: C) An oxidizing agent

The IUPAC name for CH₃CH(CH₃)CHClCH(CH₃)CH₂CH₃ is

A) 2,4-dimethyl-3-chlorohexane B) 3,5-dimethyl-4-chlorohexane C) 4-chloro-3,5-dimethylhexane D) 3-chloro-2,4-dimethylhexane

Correct Answer: D) 3-chloro-2,4-dimethylhexane

A colourless gas with a pungent smell is evolved when dilute hydrochloric acid is added to a sample of a salt. The gas evolved could turn

A) Acidified K₂Cr₂O₇ solution colourless B) Acidified KMnO₄ solution colourless C) Fe(NO₃)₂ solution green D) Pb(NO₃)₂ paper black

Correct Answer: D) Pb(NO₃)₂ paper black

If 5.0 g of marble reacts with 25.0 cm³ hydrochloric acid, which of the following combinations has the fastest reaction rate?

A) Marble chips and 2.0 mol dm⁻³ HCl(aq) B) Marble chips and 2.5 mol dm⁻³ HCl(aq) C) Powdered marble and 2.5 mol dm⁻³ HCl(aq) D) Powdered marble and 2.0 mol dm⁻³ HCl(aq)

Correct Answer: C) Powdered marble and 2.5 mol dm⁻³ HCl(aq)

Increasing the temperature generally

A) Decreases the solubility of a solid in a liquid but increases the solubility of a gas in a liquid B) Increases the solubility of a solid in a liquid but decreases the solubility of a gas in a liquid C) Increases the solubility of both a solid and a gas in a liquid D) Decreases the solubility of both a solid and a gas in a liquid

Correct Answer: B) Increases the solubility of a solid in a liquid but decreases the solubility of a gas in a liquid

A white precipitate was formed when BaCl₂(aq) was added to an aqueous solution of a salt X. The precipitate dissolved in dilute HCl with rapid effervescence. Salt X is likely to contain

A) SO₄²⁻ ions B) SO₃²⁻ ions C) NO₃⁻ ions D) CO₃²⁻ ions

Correct Answer: D) CO₃²⁻ ions

Before a reaction could take place, there should be

A) Ionization of reactant particles B) Breakage of bonds of products C) Breakage of bonds of reactants D) Ionization of product particles

Correct Answer: C) Breakage of bonds of reactants

Consider the following reaction equation:
CaO + SiO₂ → CaSiO₃
Silicon(IV) oxide is acting as

A) A basic oxide B) A reducing agent C) An acidic oxide D) An oxidizing agent

Correct Answer: C) An acidic oxide

Which of the following acids would form normal salt only?

A) Tetraoxosulphate(VI) acid B) Tetraoxophosphate(V) acid C) Trioxonitrate(V) acid D) Trioxosulphate(IV) acid

Correct Answer: C) Trioxonitrate(V) acid

What is the partial pressure of oxygen at s.t.p. in a gaseous mixture containing 100 cm³ of oxygen and 900 cm³ of nitrogen gas?

A) 1.0 atm B) 0.1 atm C) 9.0 atm D) 0.9 atm

Correct Answer: B) 0.1 atm

Graphite is used as a dry lubricant due to the presence of

A) Mobile electrons B) Free electrons C) Octahedral structures D) Layered structures

Correct Answer: D) Layered structures

Which of the following gases is alkaline?

A) NO₂ B) CO₂ C) NH₃ D) N₂O

Correct Answer: C) NH₃

Which of the following statements about an equilibrium system is correct?

A) Forward and backward reactions occur at the same rate B) The concentrations of reactants must equal that of the products C) The concentrations of reactants and products can be changed by adding a catalyst D) The concentrations of reactants and products are not affected by a change in temperature

Correct Answer: A) Forward and backward reactions occur at the same rate

Consider the following reaction equation:
N₂(g) + 3H₂(g) ⇌ 2NH₃(g), ΔH = -92 kJ
Increasing the temperature of the reaction would

A) Shift the equilibrium to the right B) Increase the yield of ammonia C) Decrease the amount of hydrogen D) Decrease the yield of ammonia

Correct Answer: D) Decrease the yield of ammonia

When air in a syringe is compressed such that there is no change in temperature, the

A) Air liquefies B) Pressure increases C) Intermolecular space increases D) Density decreases

Correct Answer: B) Pressure increases

Which of the following statements about liquids is/are true?

I. Liquids maintain their volume at constant temperature.
II. Liquids have fixed shape
III. Liquids do not diffuse
IV. Change in pressure affects volume of liquids

A) I only B) IV only C) I and IV only D) II and III only

Correct Answer: A) I only

A hydrogen chloride gas reacted with oxygen gas to yield water and chlorine gas. The mole ratio of the hydrogen chloride gas to water is

A) 1:3 B) 2:1 C) 3:1 D) 4:1

Correct Answer: B) 2:1

What number of moles of oxygen would exert a pressure of 10 atm at 320 K in an 8.2 dm³ cylinder?
[R = 0.082 atm·dm³·mol⁻¹·K⁻¹]

A) 0.32 B) 1.52 C) 3.13 D) 31.25

Correct Answer: C) 3.13

If 50 cm³ of a saturated solution of KNO₃ at 40°C contained 5.05 g of the salt, its solubility at the same temperature would be [KNO₃ = 101]

A) 1.0 mol·dm⁻³ B) 1.5 mol·dm⁻³ C) 2.0 mol·dm⁻³ D) 5.0 mol·dm⁻³

Correct Answer: A) 1.0 mol·dm⁻³

Which of the following elements would displace copper from a solution of copper ions?

A) Silver B) Gold C) Lead D) Mercury

Correct Answer: C) Lead

What is the percentage composition of carbon in Ca(HCO₃)₂? [Ca = 40.0, O = 16.0, C = 12.0, H = 1.0]

A) 22.2% B) 14.8% C) 7.4% D) 3.7%

Correct Answer: B) 14.8%

Which of the following bond types is intermolecular?

A) Covalent bond B) Hydrogen bond C) Ionic bond D) Metallic bond

Correct Answer: B) Hydrogen bond

The maximum number of covalent bonds formed by nitrogen is

A) 1 B) 2 C) 3 D) 4

Correct Answer: C) 3

The IUPAC name of the compound CH₃CH(CH₃)CH=CH₂ is

A) 2-methylbut-1-ene B) 2-methylbut-2-ene C) 3-methylbut-1-ene D) 3-methylbut-2-ene

Correct Answer: C) 3-methylbut-1-ene

Ionization energy increases across the period in the periodic table because

A) Atomic number increases B) Effective nuclear charge increases C) Mass number decreases D) Screening effect decreases

Correct Answer: B) Effective nuclear charge increases

Which of the following properties indicate that an element is a metal? It:

I. Reacts with oxygen to form an acidic oxide
II. Forms ionic chlorides
III. Has variable oxidation states
IV. Displaces hydrogen from dilute HCl

A) I and III only B) I and II only C) II and IV only D) I, II, III and IV

Correct Answer: C) II and IV only

The electron configuration of a carbon atom in its excited state is:

A) 1s² 2s² 2px² 2py⁰ B) 1s² 2s² 2px¹ 2py¹ C) 1s² 2s¹ 2px¹ 2py¹ 2pz¹ D) 1s¹ 2s² 2px¹ 2py¹

Correct Answer: C) 1s² 2s¹ 2px¹ 2py¹ 2pz¹

An oxide has the following properties:

I. It is a white powder
II. It reacts with HCl
III. It reacts with NaOH
IV. It is insoluble in water
The oxide is:

A) Alkaline B) Amphoteric C) Acidic D) Neutral

Correct Answer: B) Amphoteric

Which of the following statements about atoms of a metal is correct? They:

A) Readily accept electrons B) Are soft C) Are held together by covalent bond D) Are held together by a sea of electron cloud

Correct Answer: D) Are held together by a sea of electron cloud

Which of the following sketches is a graphical representation of Boyle's law?

A) A B) B C) C D) D

Correct Answer: C) C

The atom with the electron configuration 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁴ is

A) Period 4, p-block B) Period 3, p-block C) Period 4, d-block D) Period 3, d-block

Correct Answer: A) Period 4, p-block

Electropositivity of elements across the periodic table normally

A) Remains constant down the group B) Increases across the period C) Decreases across the period D) Decreases down the group

Correct Answer: C) Decreases across the period

Consider the following table. Which of the substances is a liquid at room temperature and rapidly evaporates on exposure to air?

Substitute	Meltig point / ºC	Boiling point / ºC
P	- 78	-25
Q	- 8	40
R	- 6	150
S	44	280

A) P B) Q C) R D) S

Correct Answer: B) Q

Which of the following oxides is amphoteric?

A) Carbon(II) oxide B) Nitrogen(IV) oxide C) Lead(II) oxide D) Calcium oxide

Correct Answer: C) Lead(II) oxide

Which of the following processes occur during fractional distillation of petroleum?

A) Condensation and diffusion B) Diffusion and evaporation C) Diffusion and sublimation D) Evaporation and condensation

Correct Answer: D) Evaporation and condensation

If the molar mass of X(HCO₃)₂ is 162 g mol⁻¹, determine the relative atomic mass of X. [H = 1.0, C = 12.0, O = 16.0]

A) 40 B) 48 C) 61 D) 101

Correct Answer: D) 101

Charcoal is used in the decolourization of sugar because of its

A) Absorption property B) Amorphous property C) Oxidizing property D) Absorption property

Correct Answer: A) Absorption property

The first definition of an element was made by

A) J. Dalton B) A. Lavoisier C) R. Boyle D) J. J. Thompson

Correct Answer: C) R. Boyle

Which of the following scientists formulated the law of conservation of mass?

A) A. Lavoisier B) J. Dalton C) R. Boyle D) J. Proust

Correct Answer: A) A. Lavoisier

Theory Questions

(a)
i. Define an acid according to the Lewis concept
ii. Give one example of a Lewis acid
(b) Explain salting out in soap preparation
(c) State the reagent and condition necessary for the following conversion
H−C≡C−H→Ag−C≡C−Ag
(d) What is the percentage abundance of an isotope?
(e)
i. Why does the element with atomic number 18 not have an oxide?
ii. Explain why chlorine(I) oxide has a low melting point
(f). Describe a test to distinguish between concentrated HNO₃ and concentrated H₂SO₄
(g) State two differences between an electrochemical cell and an electrolytic cell
(h) How does the trend in ionization energy affect the reactivity of group 1 elements?
(i).Define the term molecular formula
(j) State which of the gases H₂ and NH₃ would deviate more from ideal behaviour. Give reasons for the answer stated above

(a)
(i) Define the first ionization energy of an element
(ii) Consider the following table and use it to answer te question that follows

Element	Li	Be	b	C	N	O	F	Ne
Atomic number	3	4	5	6	7	8	9	10
1st I.E/kj mol^-1	520	900	801	1086	1402	1314	1681	2081

Explain briefly why the first ionization energy of B is less than that of Be despite the fact that the atomic number of B is greater than that of Be.
(b) When Titanium chloride was electrolysed by passing 0.12 A current through the solution for 500 seconds, 0.015 g of titanium was deposited. What is the charge on the titanium ion?
[ IF= 96500 C, Ti= 48.0 ]
(c)
(i) Aluminium can be obtained by the application of electrolysis. State the electrolyte which yields aluminium on electrolysis.
(ii) Name two major factors which would favour the siting of an aluminium smelter in a country.
(d)(i) Define the term paramagnetism.
(ii) Consider the following ions: 24Cr2+ , 24Cr6+
(I) Deduce the number of unpaired electrons in each of the ions.
(II) State which of the ions will have a greater power of paramagnetism
(l) Give a reason for the answer stated in (d)(ii)(II)

(a)
(i) Define the term Avogadro's number.
(ii) If 2.30 g of an oxide of nitrogen, x, contains 3.01 x 1022 molecules, calculate the molar mass of x.
(iii) Deduce the formula of x.
[N_A, =6.02 x 10²³, N =14.0, O = 16.0]
(b)
(i) Describe briefly what happens when each of the following substances are added to water:
(I) CCI4
(II) SiCI4
(ii) Explain briefly why the reactions in (a)(i), (b)(i), (I) and (b)(ii) (II) are different
Study the diagram below and answer the questions that follow.

What is the set-up used for?
Mention two compound that could be used as electrolytes in the cell.
Write a half-cell equation for the reaction at the anode.
Calculate the electrochemical equivalent of copper if the cathode gained mass of 3.2 g when 50 amperes of current was passed for 5 mins 13 seconds.

(a)
i. State two conditions used in the Haber process
ii. Explain briefly the effect of increasing the pressure on the rate of reaction in the Haber process.
(b)i. A mixture of nitrogen(IV) oxide and oxygen is bubbled into warm water to produce trioxonitrate(V) oxide, write a balanced chemical equation for the reaction.
ii. Using a balanced chemical equation only, explain what would happen if nitrogen(IV) oxide is bubbled into warm water.
iii. Compare the gases evolved when trioxonitrate(V) acid decomposes under each of the following properties:
i. pH
ii. Solubility in water
iii. Reaction with carbon(II) oxide
(c)
i. Name two oxides of sulphur
ii. Write a balanced equation for the reaction between each of the named oxides(Sulphur(IV) oxide, Sulphur (VI) oxide) and water
(d)
i. Name one calcium compound
a. Used to dry ammonia gas
b. Used in the manufacture of cement
c. That causes hardness in water
d. Name one calcium compound

(ii) Write a balanced equation for the reaction between each of the named oxides in 4(c)(i) and water.

(a) Describe the observation that would be made when
i. Sulphur is heated from room temperature till 1190C
ii. 50% trioxonitrate(V) acid acts on copper tunings
(b)
i. State two gaseous pollutants that can be generated by burning coal.
ii. What gas is responsible for most of the explosions in coal mines?
iii. The mining of coal leads to environmental pollution. State two environmental effects of the mining activity.
iv. Explain briefly why coal burns more easily when it is in pieces than in lump form
v. Name the non-volitile residue after the destructive distillation of coal
(c)
i. Describe a chemical test for water
ii.
a. State the effect of boiling a temporary hard water
b. State the effect of adding sodium trioxocarbonate(IV) crystals to permanent hard water
iii. Write an equation for the process of boiling a temporary hard water