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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.

38 questions JAMB 2505 WAEC 1623 NECO 168 CUSTOM 10

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Past Questions

38 questions

Question 1 of 18 38 total questions

Question 11

jamb 1998

The pH of a solution obtained by mixing 100cm\(^3\) of a 0.1M HCl solution with 100cm\(^3\) of a 0.2M solution of NaOH is?

A1.3

B7.0

C9.7

D12.7

View Explanation & Discuss

Question 12

jamb 1998

Soap lather is an example of a colloid in which a?

Aliquid is dispersed in gas

Bsolid is dispersed in liquid

Cgas is dispersed in liquid

Dliquid is despersed in liquid

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Question 13

jamb 1998

90.0g of MgCI₂ was placed in 50.0cm³ of water to give a saturated solubility of the salt is 8.0 mol dm³ at the same temperature, what is the mass of the salt left undissolved at the given temperature?

(Mg = 24, Cl = 35.5)

A52.0g

B58.5g

C85.5g

D88.5g

View Explanation & Discuss

Question 14

jamb 1998

If an element X of an atomic number Z and mass number Y is irradiated by an intense concentration of neutrons, the relevant nuclear equation is?

A^y_zX + ¹₀n → ^{y - 1}_{z + 1}X

B^y_zX + ¹₀n → ^{y + 1}_zX

C^y_zX + ¹₀n → ^y_{z + 1}X

D^y_zX + ¹₀n → ^{y + 1}_{z - 1}X

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Question 15

jamb 1998

Excess phosphorus was burnt in a gas jar and the residual gas passed successively over concentrated KOH solution and concentration H2SO4 before being collected in a flask. The gases collected are?

Acarbon (IV) oxide, nitrogen and the rare gases

Bnitrogen and the rare gases

Ccarbon (IV) oxide, nitrogen (IV) oxide and the rare gases

Dcarbon (IV) oxide

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Question 16

jamb 1998

The soil around a battery manufacturing factory is likely to contain a high concentration of?

ACa²⁺ salts

BPb²⁺ salts

CMg²⁺ salts

DAl³⁺ salts

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Question 17

jamb 1998

Potassium tetraoxomanganate (VII) is often added to impure water to?

Areduce organic impurities

Breduce inorganic impurities

Cdestroy bacteria and algae

Dremove permanent hardness

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Question 18

jamb 1998

The property used in obtaining oxygen and nitrogen industrially from air is the?

Aboiling point

Bdensity

Crate of diffusion

Dsolubility

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Question 19

jamb 1998

The line observed in the sample hydrogen spectrum are due to emission of?

Aelectrons from the atoms

Benergy by proton transition

Cenergy by electron transition

Dneutron from the atom

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Question 20

jamb 1998

Which of the following electron configurations indicates an atom with the highest ionization energy?

A2,8,7

B2,8,8,1

C2,8,8,2

D2,8,8,7

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Question 21

jamb 1998

A solid begins to melt when?

Aconstituent particles acquires a greater kinetic energy

Benergy of vibration of particles of the solid is less than the intermolecular forces

Cconstituent particles acquires energy above the average kinetic energy

Denergy of vibration of particles of the solid equals the intermolecular forces

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Question 22

jamb 1998

If sulphur (IV) oxide and methane are released simultaneously at the opposite ends of a narrow tube, the rates of diffusion Rso₂ and Rch₄ will be in the ratio?

(S = 32, O = 16, C = 12, H = 1)

A4:1

B2:1

C1:2

D1:4

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Question 23

jamb 1998

30cm³ of hydrogen was collected over water at 27°C and 780 mm Hg. If the vapour pressure of water at the temperature of the experiment was 10 mm Hg, calculate the volume of the gas at 760 mm Hg and 7°C?

A40.0 cm³

B35.7 cm³

C28.4 cm³

D25.2 cm³

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Question 24

jamb 1998

C₃H_8(g) + 50_2(g) → 4H₂O + 3CO_2(g). Form the equation above the volume of oxygen at s.t.p. required to burn 50cm³ of propane is?

A250 cm³

B150 cm³

C100 cm ³

D50 cm³

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Question 25

jamb 1998

8.0 g of an element X react with an excess of copper (ll) tetraoxosulphate (lV) solution to deposit 21.3 g of copper. The correct equation for the reaction is?

(Cu = 64).

AX_(s) + CuSO_4(aq) → Cu_(s) + XSO_4(aq)

BX_(s) + 2CuSO_4(aq) → 2Cu_(s) + X(SO₄)_2(aq)

C2X_(s) + CuSO_4(aq) → Cu_(s) + X₂SO_4(aq)

D2X_(s) + 3CuSO_4(aq) → 3Cu_(s) + X₂(SO₄)_3(aq)

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Question 26

jamb 1998

A given amount of gas occupies 10.0 dm3 at 4atm and 273°C. The number of moles of the gas present is?
(Molar volume of a gas at s.t.p. = 22.4 dm3)

A0.89 mol

B1.90 mol

C3.80 mol

D5.70 mol

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Question 27

jamb 1998

A mixture of iron and sulphur can be separated by dissolving the mixture in?

Asteam

Bdilute hydrochloric acid

Cdilute sodium hydroxide

Dbenzene

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Question 28

jamb 1998

The addition of water to calcium oxide leads to?

Aa physical change

Ba chemical change

Cthe formation of a mixture

Dan endothermic change

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