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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 1331

neco 2001

NaCl(s) does NOT conduct electricity, but N(aq) does. This is because

ANaCl(s) is non-ionic but NaCl(aq) is ion

BNaCl(aq) contains mobile electrons, where absent in NaCl(s).

CNaCl(aq) contains mobile ions which Nacl,) does not contain.

DNaCl(s) ionizes partiality while NaCl(aq) iodizes completely.

ENaCl(s) decomposes when heated but NCl(aq) is stable to heat. –

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Question 1332

neco 2001

The green colour solution of an Fe2 salt changes to a brown solution of an Fe3+ salt by

Aconversion.

Belimination.

Coxidation.

Dreduction.

Esubstitution.

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Question 1333

neco 2001

A gas X diffuse through porous partition at the rate of 3 cm₃ per second. Under the same condition hydrogen diffused at the rate of 15 cm₃ per second.

What is the 42. relative molecular mass of X.

B12

C18

D45

E50

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Question 1334

neco 2001

Faraday s first law of electrolysis can be expressed mathematically as

Am=I/it

Bmαit

CQ=it

DQαI/it

EQαit

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Question 1335

neco 2001

An experiment to test the conductance of 0,1 M solutions of the substances listed below was perform.
I ammonia
II ammonium chloride
III ethanoic acid
IV sodium ethanoate
Which pair of substances show the least conductance?

AI and II

BI and III

CI and IV

DII and III

EII and IV

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Question 1336

neco 2001

The best way to distinguish between Na₂CO₃and NaHCO₂ is by.

Aadding an acid.

Badding an alkali.

Cdissolving in water.

Dexposing to air.

Eheating.

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Question 1337

neco 2001

The Kinetic theory can NOT be used to explain

Aallotropy.

BBrownian movement.

Cdiffusion.

DTyndal effect.

Evaporization.

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Question 1338

neco 2001

The molar mass of a compound X is 56. its empirical formula is CH2. X is

Abutene.

Bbutyne.

Cethene.

Dpropene.

Epropyne

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Question 1339

neco 2001

Which compound will have the lowest boiling point?

ACH₃OH

BCH₃COOH

CCH₃CHOH

DC₄H₁₀

E(CH₃)₃CH

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Question 1340

neco 2001

The Atomic theory model which explains that electrons in an atom revolve round quantized energy levels is attributed to

ABecquerel.

BBohr.

Cde Broglie.

DRutherford.

EThompson.

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Question 1341

neco 2001

White is NOT a property of metals?

Aductile:

Bmalleable

Cconduct heat and electricity

Dhave many oxidation states

Ehigh melting points anti boiling points

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Question 1342

neco 2001

Which of the following is TRUE of a catalyst? I. it alters the activation energy of a reaction
II. it is effective in a reaction but cannot initiate a reaction
III, it affects the equilibrium of a reversible reaction
IV. it affects the overall reaction

AI and II only

BI, II and III only

CII and III only

DII, II and IV only

EIII and IV only

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Question 1343

neco 2001

The high boiling point of hydrogen fluoride can be explained in terms of

Acovalent bonds.

Bdative bonds.

Cdipole-dipole bonds.

Delectrovalent (ionic) bonds

Ehydrogen bonds.

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Question 1344

neco 2001

The oxidation number of X in \(XO_{4}^{3-}\) is

B-2

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Question 1345

neco 2001

How much sodium hydroxide is required to make 250 cm3 of 0.1 molar solution? Na=23; 0=16; H=1]

A10.0 g

B4.0g

C2.0 g

D1 .0g

E0.1 g

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Question 1346

neco 2001

What is the ratio of the rate of diffusion of carbon(IV) oxide to that of propane, under the same conditions? [H = 1; C= 12; 0= 161

A1:01

B1:10

C2:01

D2:03

E3:01

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Question 1347

neco 2001

The maximum number of electrons that can occupy the shell having a principal quantum number of 3 is

C10

D18

E32

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Question 1348

neco 2001

On exposure to hydrogen sulphide, moist lead (II) ethanoate paper turns

Ablack

Bblue

Cgreen

Dwhite

Eyellow

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Question 1349

neco 2001

Which compound is a product of the hydrolysis of the of CH\(_3\)COOC\(_3\)H\(_7\) with aqueous sodium hydroxide?

ACH₃COONa

BCH₃COONaCCH₃OH

CCH₃OH

DC₂H₅OH

EC₃H₇COONa

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Question 1350

neco 2001

The alloy used for welding and plumbing contains

Aaluminum and copper.

Bcopper and tin

Ciron and aluminum.

Dlead and antimony.

Elead and tin.

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