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Chemistry Past Questions

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82 questions JAMB 2505 WAEC 1623 NECO 168 CUSTOM 10

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82 questions

Question 1 of 20 82 total questions

Question 31

jamb 1989

Which of the following represents the balanced equation for the reaction of copper with concentrated trioxonitrate (V) acid?

ACu _(s) + 2HNO _3(aq) → Cu (NO ₃) _2(aq) + H _2(g)

BCu _(s) + 4HNO _3(aq) → Cu (NO ₃) _2(aq) + 2H ₂O ₍₁₎ + 2NO _2(g)

C3Cu _(s) + 8HNO_3(aq) → 3Cu (NO₃)_2(aq) + 4H₂O₍₁₎ + 2NO_(g)

D3Cu_(s) + 4HNO_3(aq) → 3Cu(NO ₃) _2(aq) + 2H ₂O ₍₁₎ + 2NO _(g)

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Question 32

jamb 1989

The combustion of ethene, C ₂H ₄, is given by the equation C ₂H ₄ + 30 ₂ → 2CO₂ + 2H₂ O; ∆H = - 1428 KJ. If the molar heats of formation of water and carbon (IV) oxide are - 286 kJ and - 396 kJ respectively, calculate the molar heat of formation of ethene in KJ

A- 2792

B+ 2792

C- 64

D+ 64

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Question 33

jamb 1989

An element, Z froms an anion whose formula is [Z(CN)₆]^y. If Z has an oxidation number of +2, what is the value of y?

A- 2

B- 3

C- 4

D- 5

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Question 34

jamb 1989

What is discharged at the cathode during the electrolysis of copper (ll) tetraoxosulphate (VI) solution?

ACu ²⁺ only

BH + only

CCu ²⁺ and H

DCu ²⁺ and SO ^2-

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Question 35

jamb 1989

The same current is passed for the same time through solutions of AgNO₃ and CuSO₄ connected in series. How much silver will be deposited if 1.0 g of copper is produced?
[Cu = 63.5, S = 32, O = 16, Ag = 108, N = 14]

A1.7 g

B3.4 g

C6. 8 g

D13. 6 g

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Question 36

jamb 1989

An acid and its conjugate base

Acan neutralise each other to form a salt

Bdiffer only by a proton

Cdiffer only by the opposite charges they carry

Dare always neutral substances

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Question 37

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 38

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 39

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 40

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 41

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 42

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 43

jamb 1989

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

C15

D31

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Question 44

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 45

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 46

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 47

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 48

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 49

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 50

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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