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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 1281

waec 2002

The following compounds are hydrocarbons except

Amethylpropanoate

B2-methylbutane

Cbenzene

Dcyclohexane

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Question 1282

waec 2002

When alkynes are hydrogenated completely they produce compounds with the general molecular formula

AC_nH_n

BC_nH_2n

CC_nH_2n+2

DC_nH_2n-2

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Question 1283

waec 2002

Which of the following compounds can be represented by the molecular formula C₂H₆O?

APropanal

BEthanol

CMethanoic acid

DGlucose

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Question 1284

waec 2002

Which of the following processes takes place during the production of margarine from vegetable oils?

AEsterification

BHydrolysis

CHydrogenation

DSaponification

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Question 1285

waec 2002

When concentrated sodium chloride solution is electrolysed using inert electrodes, the products are

Aoxygen and hydrogen

Bhydrogen and chlorine

Csodium and oxygen

Dsodium and chlorine

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Question 1286

waec 2002

If two metallic ions of the same concentration migrate to a graphite cathode, the one that would be preferentially discharged is the one that has the

Asmaller mass

Blower electrical charge

Cgreater stability in solution

Dstronger tendency to accept electrons

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Question 1287

waec 2002

Which of the following ions require the largest quantity of electricity for discharge at an electrode?

A2.0 mole of Q ³⁺

B2.5 mole of R²⁺

C3.0 mole of T^-

D4.0 mole of Y^-

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Question 1288

waec 2002

Consider the following equation: Cr\(_2\)O\(_7\)\(^{2-}\)(aq) + 14H\(^+\)(aq) + 6e\(^-\) → 2Cr\(^{3+}\)(ag) + 7H\(_2\)O(1). The oxidation number of chromium changes from

A-2 to + 3

B-2 to + 6

C+6 to +3

D+7 to + 6

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Question 1289

waec 2002

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 1290

waec 2002

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

ACu(NO₃)₂

BAgNO₃

CK₂CO₃

DCaCO₃

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Question 1291

waec 2002

CuSO₄5H₂O 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 1292

waec 2002

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 evoluton of gas

BTotal mass of gas evolved during the reaction

CTime taken for the reaction to reach completion

DInitial reaction rates

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Question 1293

waec 2002

What is the expression for the equilibrium constant (Kc) for the following reaction? N2(g) + O2(g) ⇌ 2NO(g)

A\(\frac{[NO^2]}{[N^2] + [O^2]}\)

B\(\frac{[2NO]^2}{[N_2][O_2]}\)

C\(\frac{[N_2] + [O_2]}{2[NO]^2}\)

D\(\frac{[NO]^2}{[N_2][O_2]}\)

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Question 1294

waec 2002

What will happen if more heat is applied to the following system at equilibrium?

X\(_2\)(g) + 3Y\(_2\)(g) ⇌ 2XY\(_3\)(g); ∆H = xKJmol\(^{-1}\)

Athe yield of XY ₃ will decompose

Bmore of XY₃ will decompose

CMore of X₂ will react

Dthe forward reaction will remain static

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Question 1295

waec 2002

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

ANaCI_(aq)

BNa₂CO_3(aq)

CNa₂SO_4(aq)

DNaHSO_4(aq)

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Question 1296

waec 2002

Calculate the mass of sodium hydroxide in 5.00 dm³ of a 0.125 mol dm^-3 solution. [NaOH = 40 g mol^-1]

A0.0156 g

B0.625 g

C1.00 g

D25.0 g

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Question 1297

waec 2002

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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Question 1298

waec 2002

A substance is said to be hygroscopic if it absorbs

Awater from the atmosphere to form a solution

Bheat from the surrounding

Ccarbon (IV) oxide from the atmosphere

Dmoisture from the atmosphere without dissolving

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Question 1299

waec 2002

Which of following acids forms normal salts only?

ATetraoxosulphate (VI) acid

BTrioxosulphate (IV) acid

CAcetic acid

DTetraoxophosphate (V) acid

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Question 1300

waec 2002

A major factor considered in selecting a suitable method for preparing a simple salt is its

Acrystalline form

Bmelting point

Creactivity with dilute acids

Dsolubility in water

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