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Chemistry Past Questions

Study and practice Chemistry past questions with answers and detailed explanations. Then test your knowledge using our interactive CBT practice platform and prepare confidently for your upcoming examinations.

138 questions JAMB 2505 WAEC 1623 NECO 168 CUSTOM 10

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Past Questions

138 questions

Question 1 of 20 138 total questions

Question 1

waec 2023

How many moles of copper would be deposited by passing 1 Faraday of electricity through a \(CuCl_2\) solution?

A2 moles

B0.5moles

C0.025moles

D1 mole

View Explanation & Discuss

Question 2

waec 2023

How many grammes of NaOH(s) would be needed to produce 100.0 cm3 of a 0.20 mol dm-3 NaOH, (aq)? [NaOH = 40.0]

A800.0g

B0.02 g

C20.0 g

D0.80 g

View Explanation & Discuss

Question 3

waec 2023

Thermal cracking of alkanes usually

Ais an exothermic process

Bproduces only small alkanes

Cinvolves decomposition

Drequires hydrogen

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Question 4

waec 2023

The relative molar mass of a gaseous hydrocarbon is 30. Determine its vapour density.

A45

B30

C15

D60

View Explanation & Discuss

Question 5

waec 2023

The best indicator to use for the titration of ethanoic acid with sodium hydroxide is

Amethyl orange

Bphenolphthalein

Cscreened methyl orange

Dmethyl red

View Explanation & Discuss

Question 6

waec 2023

An example of a crystalline substance that does not possess water of crystallization is

Apotassium trioxonitrate (V)

Bsodium tetraoxosulphate (VI).

Ciron (II) tetraoxosulphate (VI)

Dsodium trioxocarbonate (IV).

View Explanation & Discuss

Question 7

waec 2023

Which of the following gases has the lowest rate of diffusion?
[H=1.0, C=12.0, N = 14.0, O= 16.0]

ANitrogen

Bmethane

CAmmonia

DOxygen

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Question 8

waec 2023

Isoelectronic species have the same number of

Aions

Belectrons

Cprotons

Dneutrons

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Question 9

waec 2023

Why are \(H_2SO_4\) and \(CaCl_2\), not suitable for drying ammonia gas? They

Aare poisonous.

Bpollute the gas

Care corrosive

Dreact with the gas

View Explanation & Discuss

Question 10

waec 2023

The reduction half equation of the following reaction is:
\(Zn_{(s)} + CuSO_{4(aq)} → ZnSO_{4(aq)} + Cu_{(s)}\)

A\(Zn_{(s)} → Zn^{2+}_{(aq)} + 2e^-\)

B\(CuSO_{4(s)} + H_2O_{(l)}\) → \(Cu^{2+}_{(aq)}\) +
\(SO_{4(aq)}^{2-}\)

C\(Cu^{2+}_{(aq)} + 2e^- → Cu_{(s)}\)

D\(Cu^{2+}_{(aq)} + e^- → Cu_{(s)}\)

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Question 11

waec 2023

The molecule that has a non-polar covalent bond is

AHCl

B\(NH_3\)

C\(Cl_2\)

D\(H_2O\)

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Question 12

waec 2023

Petrochemistry is an example of

Aapplied chemistry

BBiochemistry

CPure chemistry

DEnvironmental chemistry

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Question 13

waec 2023

Which of the following elements has its valence electrons in the s-orbital?

AAluminum

BPhosphorus

CSodium

DCarbon

View Explanation & Discuss

Question 14

waec 2023

Which of the following statements about the collision theory is correct?

AIneffective collision brings about chemical reaction

BAll collisions bring about reactions

CThe rate of reaction is proportional to the number of effective collisions

DCollision of molecules will split the molecules to react

View Explanation & Discuss

Question 15

waec 2023

An element X has two isotopes, \(^{65}X_{30}\) and \(^{66}X_{30}\) with relative abundance of 60 % and 40% respectively. The relative atomic mass of X is

A66.00

B65.50

C65.00

D65.40

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Question 16

waec 2023

Positive ions in a sea of electrons are found in

Acovalent bonds

Bmetallic bonds

Cdative bonds

Dionic bonds

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Question 17

waec 2023

Determine the volume of 0.100 mol of HCl in \(0.250 mol dm^3\) of solution.

A\(200cm^3\)

B\(100cm^3\)

C\(20cm^3\)

D\(400cm^3\)

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Question 18

waec 2023

Which of the statements about gases is not correct?

AGases have low densities compared to solids and liquids of equal mass.

BThe total kinetic energy of the gas is not affected by collision

CMolecules of the gas are in constant motion

DGases are highly soluble in water at high temperatures

View Explanation & Discuss

Question 19

waec 2023

A compound that could be dried by using conc. tetraoxosulphate (VI) acid and not by calcium oxide is likely to be

Aa deliquescent salt

Ba neutral salt

Can alkaline gas

Dan acid anhydride

View Explanation & Discuss

Question 20

waec 2023

If \(100^3\) of a saturated solution of sodium tetraoxosulphate (VI) at 30° C contains 10.5 g of the salt, what would be its solubility at this temperature? [(\(Na_2SO_4\) = 142]

A2.15 mol dm-3

B0.74 mol dm-3

C0.60 mol dm-3

D0.57 mol dm-3

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