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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

Question 1 of 20 4,306 total questions

Question 1341

neco 2001

in any chemical reaction, the total mass of products is always equal to that of the reactants.

This Is statement of the law of:

Aconservation of matter.

BConstant composition

Cdefinite proportions.

Dmultiple proportions.

Ereciprocal proportions.

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Question 1342

neco 2001

Which metal will dissolve in aqueous sodium hydroxide?

Aaluminium

Bcopper

Ciron

Dsikeer

Etin

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Question 1343

neco 2001

Which compound can be used as a reducing agent in a reaction?

ACl₂

BKMnO₄

CKCr₂O₇

DMnO₂

ENa₂SO₃

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Question 1344

neco 2001

what dose the following equation illustrate? \( ^{238}U_{92} → ^{234}Th_{90} + ^4 He_2 \)

AArtificial radioactivity

Bnuclear fission

Cnuclear fusion

Dradio-decomposition

Espontaneous disintegration

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Question 1345

neco 2001

The position of an element in the Periodic Table is determined by?

Aits atomic radius.

Bits density.

Cits relative atomic mass.

Dthe number of protons in its atom.

Ethe number of neutrons in its atoms

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Question 1346

neco 2001

Which element contains the greatest number of moles?

A8 g of Helium

B48 g of Carbon

C78 g of Potassium

D130g of Zinc

E216g of Sliver

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Question 1347

neco 2001

The use of sulphur to vulcanize rubber is made to make it

Ablacker.

Bcheaper. .

Cmore elastic

Dtougher

Esofter.

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Question 1348

neco 2001

The atomic number of iron is 56. The number of unpaired electrons in the Fe3+ ion is

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Question 1349

neco 2001

Animal charcoal differs from wood charcoal in that it

Ahas a dark colour

Bhas a high carbon content

Cis a good absorbent

Dis crystalline.

Eis rich in phosphate content

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Question 1350

neco 2001

Which statement BEST describes the process of oxidation?

Aaddition of hydrogen

Bloss of oxygen

Cdecrease in oxidation number

Dloss of electrons

Egain of elections.

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Question 1351

neco 2001

The decreasing order of the oxidising power of the halogens is

ABr>I>Cl>F

BF>I>Cl>Br

CF>Cl>Br>l

DI>Br>Cl>F

ECl>Br>F>I

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Question 1352

neco 2001

20 cm\(^3\) of 0.09 mol dm\(^{-3}\) solution of tetraoxosuiphate (Vi) acid requires 30cm\(^3\) of sodium hydroxide solution for complete neutralization. The molar concentration of sodium hydroxide is [H = 1; S = 32; 0 = 16; Na = 23]

A0.03 mol dm³

B0.12 mol dm³

C0.27 mol dm³

D0.45 mol dm³

E0.90 mol dm³

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Question 1353

waec 2001

A visible change is observed when a strip of iron is placed in an aqueous solution of

AFeSO₄

BZnSO₄

CCuSO₄

DMgSO₄

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Question 1354

waec 2001

Which of the compounds will leave a metal residue when heated?

ACu(NO ₃ )₂

BAgNO₃

CK₂CO₃

DCaCO₃

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Question 1355

waec 2001

CuSO4 5H2O can be obtained from an aqueous solution of copper (ll) tetraoxosulphate (VI) by

Aevaporation to dryness

Busing chromatography

Cprecipitation

Dcrystallization

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Question 1356

waec 2001

Equal amounts of marble chips are reacted separately with 100cm3 of hydrochloric acid of different concentrations . if all the marble chips reacted, which of the following remained the same in each case?

AAverage rate of evolution of gas

BTotal mass of gas evolved during the reaction

CTime taken for the reaction to reach completion

Dlnitial reaction rates

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Question 1357

waec 2001

What will happen if more heat is applied to the following system at equilibrium? X2(g) + 3Y 2(g) ⇌ 2XY3(g); ∆H =-kJmol -1

Athe yield of XY ₃ will decompose

Bmore of XY₃ will decompose

CMore of X₂ will react

Dthe forward reaction will go to completion

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Question 1358

waec 2001

Which of the following salt solutions will have a pH greater than 7?

ANaCl_(aq)

BNa₂CO_3(aq)

CNa₂SO_4(aq)

DNaHSO_4(aq)

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Question 1359

waec 2001

Calculate the mass of sodium hydroxide in 5.00 dm3 of a 0.125 mol dm-3 solution [NaOH = 40 g mol]

A0.0156 g

B0.625 g

C1.00 g

D25. 0 g

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Question 1360

waec 2001

Which of the following substances increases in mass when heated in air?

ASodium chloride

Blodine crystals

Cmagnesium ribbon

Dcopper (ll) oxide

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