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Chemistry Past Questions

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4,306 questions JAMB 2505 WAEC 1623 NECO 168 CUSTOM 10

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4,306 questions

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Question 1871

jamb 1989

The substance ZnO dissolves in sodium hydroxide solution and mineral acid solution to give soluble products in each case. ZnO is therefore referred to as

Aan allotropic oxide

Ban amphoteric oxide

Ca peroxide

Da dioxide

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Question 1872

jamb 1989

A solution of calcium bromide contains 20 g dm\(^3\). What is the molarity of the solution with respect to calcium bromide and bromide ions? [Ca = 40, Br = 80]

A0. 1, 0 . 1

B0. 1, 0. 2

C0. 1, 0. 05

D0.05, 0.1

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Question 1873

jamb 1989

Using 50 cm\(^3\) of 1 M potassium hydroxide and 100 cm\(^3\) of 1 M tetraoxosulphate (VI) acid, calculate the respective volumes in cm\(^3\) of base and acid that would be required to produce the maximum amount of potassium tetraoxosulphate (IV) [K = 39, S = 32, O = 16, H = 1]

A50, 50

B25, 50

C50, 25

D25, 25

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Question 1874

jamb 1989

A hydrated salt of formula MSO4.xH2 O CONTAINS 45.3% by mass of water of crystalisation. Calculate the value of x [M = 56, S = 32, O = 16, H = 1 ]

D10

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Question 1875

jamb 1989

Calcium hydroxide is added in the treatment of town water supply to

Akill bacteria in the water

Bfacilitate coagulation of organic particles

Cfacilitate sedimentation

Dimprove the taste of the water

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Question 1876

jamb 1989

The gaseous pollutant sulphur (IV)oxide is most likely to be detected in fairly reasonable quantities in the area around a plant for the

Aextraction of aluminium from bauxite

Bproduction of margarine

Csmelting of copper

Dproduction of chlorine from brine

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Question 1877

jamb 1989

How many valence electrons are contained in the element represented \(^{31}\) \(_{15}\)P?

C15

D31

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Question 1878

jamb 1989

Four elements P,Q, R and S have atomic numbers of 4, 10, 12 and 14 respectively . Which of these electrons is a noble gas?

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Question 1879

jamb 1989

The atomic number of caesium is 55 and its atomic mass is 133. The nucleus of caesium atom therefore contains

A78 protons and 55 elections

B55 protons and 78 neutrons

C55 neutrons 78 electrons

D78 protons and 55 neutrons

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Question 1880

jamb 1989

Elements X and Y have electronic configurations 1s\(^2\)2s\(^2\)2p\(^4\) and 1s\(^2\)2s\(^2\)2p\(^6\)3s\(^2\)3p\(^1\) respectively. When they combine, the formula of the compound formed is?

AXY

BYX

CX₂Y₃

DY₂X₃

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Question 1881

jamb 1989

The atomic radius of Li, Na and K are 1: 33A, 1. 54A and 1. 96A res pectively. Which of the following explaqins this gradation in atomic radius?

Aelectropositivity decreases from Li to Na to K

Belectronegativity decreases from Li to Na to K

Cthe number of the electron shells increases from Li to Na to K

Dthe elements are in the same period

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Question 1882

jamb 1989

What is the partial pressure of hydrogen gas collected
over water at standard atmospheric pressure and 25 ^oC if the saturation vapour pressure of water at saturation vapour pressure of water is 23 mm Hg at that temperature?

A737 mm Hg

B763 mm Hg

C777 mm Hg

D783 mm Hg

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Question 1883

jamb 1989

The minimum volume of oxygen required for the complete combustion of a mixture of 10cm 3 of CO and 15 cm 3 of H 2 is

A25.0cm³

B12.5 cm³

C10.0 cm³

D5.0cm³

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Question 1884

jamb 1989

20.00 cm\(^3\) of a solution containing 0.53 g of anhydrous Na\(_2\)CO\(_3\) in 100 cm\(^3\) requires 25.00 cm\(^3\) of H\(_2\)SO\(_4\) for complete neutralisation. The concentration of the acid solution in moles per dm\(^3\) is [H =1, C = 12, O = 16, Na =23, S = 32]

A0.02

B0.04

C0.06

D0.08

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Question 1885

jamb 1989

The molar ratio of carbon to hydrogen of a volatile liquid compound is 1: 2. 0. 12 g of the liquid on evaporation at s.t.p. gave 32 cm³ of vapour. The molecular formula of the liquid is
[G.M.V =22.4 dm ³, C = 12, H = 1]

AC ₃ H ₆

BC ₄H ₈

CC ₅C ₁₀

DC ₆H ₁₂

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Question 1886

jamb 1989

Which of the following would support the conclusion that a solid sample is a mixture?

Athe solid can be ground to a fine powder

Bthe density of the solid is 2.25 g dm³

Cthe solid has a melting range of 300^oC to 375^oC

Dthe solid absorbs moisture from the atmosphere

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Question 1887

waec 1988

During the electrolysis of dilute tetraoxosulphate (VI) acid solution 0.05 mole of electrons were passed what volume of gas was produced at the anode? (Gaseous molar volume = 22. 4dm³ at s.t.p)

A0.224 dm³

B0.280 dm³

C0.560 dm³

D2.24 dm³

E22.4 dm³

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Question 1888

waec 1988

The reaction represented by the equation C_(s) + H₂O_(l) → CO_(s) + H ₂_(s) was carried out at 27_oC if the enthalpy change was + 4500 J and the entropy change was + 12J, what was the free energy change? (∆G = ∆H - T∆S)

A- 4176 J

B+4176 J

C- 900 J

D+ 900 J

E+8100 J

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Question 1889

waec 1988

The complex salt formed when aluminium dissolves in sodium hydroxide solution is

ANa₃AI(OH)₄

BNa₂AI(OH)3

CNaAI(OH)₃

DNa₄AI(OH)₄

ENaAI(OH)₄

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Question 1890

waec 1988

When copper (ll) chloride solution is treated with excess aqueous ammonia, a deep blue solution results This is due to the presence of

A(CuNH₄)³⁺ ions

B(CuCI₄)^2-ions

C[Cu(OH)₄]^2- ions

DCu(H^2-O)₄²⁺ IONS

E[cU(NH₃)₄]^ions

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