Chemistry past questions: WAEC SSCE 2022

48 objective questions, with answers. Free to read and practise.

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48 questions, one at a time, marked as you go or at the end. No account needed.

1.
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
1. A.acidified K \(_{2}\) Cr \(_{2}\) O \(_{7}\) solution colourless
2. B.acidified KMnO \(_{4}\) solution colourless
3. C.Fe(NO \(_{3}\) ) \(_{2}\) solution green
4. D.Pb(NO \(_{3}\) ) \(_{2}\) paper black
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Answer: B acidified KMnO \(_{4}\) solution colourless
2.
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
1. A.1:3
2. B.2:1
3. C.3:1
4. D.4:1
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Answer: B 2:1
3.
A white precipitate was formed when BaCl \(_{2(aq)}\) 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
1. A.SO \(_{4}\) \(^{2-}\) ions
2. B.SO \(_{3}\) \(^{2-}\) ions
3. C.NO \(_{3}\) - ions
4. D.CO \(_{3}\) \(^{2-}\) - ions
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Answer: B SO \(_{3}\) \(^{2-}\) ions
4.
Alkanols can be manufactured from alkenes by the initial reaction of alkenes with
1. A.bromine in tetrachloromethane
2. B.concentrated tetraoxosulphate(VI) acid
3. C.aqueous potassium tetraoxomanganate(VII)
4. D.sodium hydroxide solution
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Answer: B concentrated tetraoxosulphate(VI) acid
5.
An oxide has the following properties. It I. is a white powder II. reacts with HCI. III. reacts with NaOH IV. is insoluble in water The oxide is
1. A.alkaline
2. B.amphoteric
3. C.acidic
4. D.neutral
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Answer: B amphoteric
6.
Charcoal is used in the decolourization of sugar because of its
1. A.absorption property.
2. B.amorphous property.
3. C.oxidizing property.
4. D.adsorption property.
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Answer: D adsorption property.
7.
Consider the following reaction equation N \(_{2}\) (g) + 3H \(_{2(g)}\) ⇌ 2NH3(g) ∆H = -92kJ Increasing the temperature of the reaction would
1. A.shift the equilibrium to the right
2. B.increase the yield of ammonia
3. C.decrease the amount of hydrogen
4. D.decrease the yield of ammonia
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Answer: D decrease the yield of ammonia
8.
Consider the following reaction equation: CaO + SiO \(_{2}\) ------> CaSiO \(_{3}\) Silicon(IV) oxide is acting as
1. A.a basic oxide
2. B.a reducing agent
3. C.an acidic oxide
4. D.an oxidizing agent
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Answer: C an acidic oxide
9.
Consider the following table
Substitute Meltig point / ºC Boiling point / ºC
P - 78 -25
Q - 8 40
R - 6 150
S 44 280
Which of the substances is a liquid at room temperature and rapidly evaporates on exposure to air?
1. A.P
2. B.Q
3. C.R
4. D.S
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Answer: B Q
10.
Determine the quantity of electricity used when a current of 0.20 amperes is passed through an electrolytic cell for 60 minutes.
1. A.12C
2. B.120C
3. C.360C
4. D.720C
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Answer: D 720C
11.
Electropositivity of elements across the periodic table normally
1. A.remains constant down the group
2. B.increases across the period
3. C.decreases across the period
4. D.decreases down the group
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Answer: C decreases across the period
12.
Graphite is used as a dry lubricant due to the presence of
1. A.mobile electrons
2. B.free electrons
3. C.octahedral structures
4. D.layered structures
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Answer: D layered structures
13.
If 5.0 g of marble reacts with 25.0 cm3 hydrochloric acid, which of the following combinations has the fastest reaction rate?
1. A.Marble chips and 2.0 mol dm \(^{-3}\) HCl \(_{(aq)}\)
2. B.Marble chips and 2.5 mol dm \(^{-3}\) HCl \(_{(aq)}\)
3. C.Powdered marble and 2.5 mol dm \(^{-3}\) HCl \(_{(aq)}\)
4. D.Powdered marble and 2.0 mol dm \(^{-3}\) HCl \(_{(aq)}\)
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Answer: C Powdered marble and 2.5 mol dm \(^{-3}\) HCl \(_{(aq)}\)
14.
If 50 cm \(^{3}\) of a saturated solution of KNO \(_{3}\) at 40 °C contained 5.05 g of the salt, its solubility at the same temperature would be [KNO \(_{3}\) = 101]
1. A.1.0 mol dm \(^{-3}\)
2. B.1.5 mol dm \(^{-3}\)
3. C.2.0 mol dm \(^{-3}\)
4. D.5.0 mol dm \(^{-3}\)
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Answer: A 1.0 mol dm \(^{-3}\)
15.
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)
1. A.MO
2. B.MO \(_{2}\)
3. C.MO \(_{3}\)
4. D.MO \(_{4}\)
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Answer: C MO \(_{3}\)
16.
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, 0 = 16.0]
1. A.40
2. B.48
3. C.61
4. D.101
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Answer: A 40
17.
Increasing the temperature generally
1. A.decreases the solubility of a solid in a liquid but increases the solubility of a gas in a liquid
2. B.increases the solubility of a solid in a liquid but decreases the solubility of a gas in a liquid
3. C.increases the solubility of both a solid and a gas in a liquid
4. D.decreases the solubility of both a solid and a gas in a liquid
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Answer: B increases the solubility of a solid in a liquid but decreases the solubility of a gas in a liquid
18.
Ionization energy increases across the period in the periodic table because
1. A.atomic number increases
2. B.effective nuclear charge increases
3. C.mass number decreases
4. D.screening effect decreases
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Answer: B effective nuclear charge increases
19.
Oxochlorate(I) acid is used as a bleaching agent because it is
1. A.a weak acid
2. B.a reducing agent
3. C.an oxidizing agent
4. D.a strong acid
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Answer: C an oxidizing agent
20.
The atom with the electron configuration 1s \(^{2}\) 2s \(^{2}\) 2p63s \(^{2}\) 3p \(^{6}\) 3d \(^{10}\) 4s \(^{2}\) 4p \(^{4}\) is in
1. A.period 4, p- block
2. B.period 3, p- block
3. C.period 4, d- block
4. D.period 3, d- block
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Answer: A period 4, p- block
21.
The by-product of fermentation of sugar is
1. A.carbon(IV) oxide
2. B.ethanoic acid
3. C.propanol
4. D.propan-1, 2, 3- triol
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Answer: A carbon(IV) oxide
22.
The cleansing effect of soap is low in acidic water because of
1. A.the formation of unionized fatty acid
2. B.increase in the pH of the soap molecules
3. C.anti-biodegradable effect of hydrogen ions
4. D.the hardness of the acidic water
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Answer: A the formation of unionized fatty acid
23.
The first definition of an element was made by
1. A.J. Dalton.
2. B.A. Lavoisier.
3. C.R. Boyle.
4. D.J. J. Thompson.
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Answer: C R. Boyle.
24.
The following compounds are condensation polymers except
1. A.nylon
2. B.protein
3. C.starch
4. D.polyethene
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Answer: D polyethene
25.
The IUPAC name for CH \(_{3}\) CHCH \(_{3}\) CHCLCHCH \(_{3}\) CH \(_{2}\) CH \(_{3}\) is
1. A.2, 4 - dimethyl - 3 - chlorohexane
2. B.3, 5 - dimethyl - 4 - chlorohexane
3. C.4 - chloro - 3, 5 - dirnethylhexane
4. D.3 - chloro - 2, 4 - dimethylhexane
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Answer: D 3 - chloro - 2, 4 - dimethylhexane
26.
The IUPAC name of the compound CH3CH(CH3)CHCH2 is
1. A.2 - methyl but - 1 - ene
2. B.2 - methyl but - 2 - ene
3. C.3 - methyl but - 1 - ene
4. D.3 - methyl but - 2 - ene
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Answer: C 3 - methyl but - 1 - ene
27.
The maximum number of covalent bonds formed by nitrogen is
1. A.1
2. B.2
3. C.3
4. D.4
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Answer: D 4
28.
The products of the electrolysis of dilute sodium chloride using carbon electrodes are Anode Cathode
1. A.chlorine and sodium.
2. B.oxygen and hydrogen.
3. C.chlorine and hydrogen.
4. D.hydrogen and oxygen.
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Answer: B oxygen and hydrogen.
29.
What amount of electricity is required to deposit one mole of aluminium from a solution of AlCl3?
1. A.One Faraday
2. B.One ampere
3. C.Three Faradays
4. D.Three amperes
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Answer: C Three Faradays
30.
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?
1. A.1.0 atm
2. B.0.1 atm
3. C.9.0 atm
4. D.0.9 atm
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Answer: B 0.1 atm
31.
What is the percentage composition of carbon in Ca(HCO3) \(_{2}\) ? [ Ca = 40.0, 0= 16.0, C = 12.0, H= 1.0]
1. A.22.2%
2. B.14.8%
3. C.7.4%
4. D.3.7%
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Answer: B 14.8%
32.
What number of moles of oxygen would exert a pressure of 10 atm at 320 K in an 8.2 dm \(^{3}\) cylinder? [R=0.082 atm dm \(^{-3}\) mol \(^{-1}\) K \(^{-1}\) ]
1. A.0.32
2. B.1.52
3. C.3.13
4. D.31.25
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Answer: C 3.13
33.
When air in a syringe is compressed such that there is no change in temperature, the
1. A.air liquefies
2. B.pressure increases
3. C.intermolecular space increases
4. D.density decreases
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Answer: B pressure increases
34.
Which of the following acids would form normal salt only?
1. A.Tetraoxosulphate(VI) acid
2. B.Trioxonitrate(V) acid
3. C.Tetraoxophosphate(V) acid
4. D.Trioxosulphate(IV) acid
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Answer: B Trioxonitrate(V) acid
35.
Which of the following bond types is intermolecular?
1. A.Covalent bond
2. B.Hydrogen bond
3. C.Ionic bond
4. D.Metallic bond
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Answer: B Hydrogen bond
36.
Which of the following compounds would react rapidly with bromine?
1. A.Benzene
2. B.Hexane
3. C.Hexene
4. D.Hexanol
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Answer: C Hexene
37.
Which of the following elements would displace copper from a solution of copper ions?
1. A.silver
2. B.gold
3. C.lead
4. D.mercury
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Answer: C lead
38.
Which of the following gases is alkaline?
1. A.NO \(_{2}\)
2. B.CO \(_{2}\)
3. C.NH \(_{3}\)
4. D.N \(_{2}\) O
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Answer: C NH \(_{3}\)
39.
Which of the following oxides is amphoteric?
1. A.Carbon(II) oxide
2. B.Nitrogen(IV) oxide
3. C.Lead(II) oxide
4. D.Calcium oxide
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Answer: C Lead(II) oxide
40.
Which of the following processes occur during fractional distillation of petroleum?
1. A.Condensation and diffusion
2. B.Diffusion and evaporation
3. C.Diffusion and sublimation
4. D.Evaporation and condensation
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Answer: D Evaporation and condensation
41.
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
1. A.I and III only
2. B.I and II only
3. C.II and IV only
4. D.I, II, III and IV
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Answer: C II and IV only
42.
Which of the following scientists formulated the law of conservation of mass?
1. A.A. Lavoisier
2. B.J. Dalton
3. C.R. Boyle
4. D.J. Proust
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Answer: A A. Lavoisier
43.
Which of the following sketches is a graphical representation of Boyle's law?
1. A.A
2. B.B
3. C.C
4. D.D
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Answer: C C
44.
Which of the following statements about an equilibrium system is correct?
1. A.Forward and backward reactions occur at the same rate
2. B.The concentrations of reactants must equal that of the products
3. C.The concentrations of, reactants and products can be changed by adding a catalyst,
4. D.The concentrations of reactants and products are not affected by a change in temperature
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Answer: A Forward and backward reactions occur at the same rate
45.
Which of the following statements about atoms of a metal is correct? They
1. A.readily accept electrons
2. B.are soft
3. C.are held together by covalent bond
4. D.are held together by a sea of electron cloud
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Answer: D are held together by a sea of electron cloud
46.
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
1. A.I only
2. B.IV only
3. C.I and IV only
4. D.II and III only
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Answer: A I only
47.
Which of the following statements about the standard hydrogen electrode is not correct?
1. A.The hydrogen gas is at a pressure of 1 atmosphere
2. B.A solution containing 1 mol dm-3 of H+ (aq) ions is used
3. C.A platinum electrode is used
4. D.The temperature is kept at 20 °C
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Answer: D The temperature is kept at 20 °C
48.
Which of the following sugars is a product of the condensation of monosaccharides?
1. A.galactose
2. B.maltose
3. C.glucose
4. D.fructose
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Answer: B maltose

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