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Chemistry Past Questions

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168 questions JAMB 2505 WAEC 1623 NECO 168 CUSTOM 10

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168 questions

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Question 51

neco 2003

Ethene decolourises acidified potassium tetraoxomanganate(VII) solution. Which gas will decolourise bromine water?

ACH₄

BC₂H₆

CC₃H₆

DC₃H₈

EC₆H₆

View Explanation & Discuss

Question 52

neco 2003

Which method is used for the purification of copper from its ore?

Adistillation

Belectrochemical

Celectrolysis

Dneutralization

Ereduction

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Question 53

neco 2003

What is the concentration (mol dm\(^{-3}\)) of a solution containing 28 g of potassium hydroxide per 100 cm\(^3\) of solution? (K=39; H=1; O=16)

A0.01

B0.05

C1.0

D5.0

E2.8

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Question 54

neco 2003

At s.t.p, a mole of chlorine occupies 22.4dm3. If the temperature is changed to 35°C and the pressure to 750mHg the of the new volume will be [Cl = 35.5]

A\(\frac{760\times 22.4\times 308}{750\times 273\times 35.5} dm^3 \)

B\(\frac{760\times 22.4\times 308}{750\times 273}dm^3 \)

C\(\frac{750\times 22.4\times 35.5}{760\times 273}dm^3\)

D\(\frac{760\times 22.4\times 35.5}{750\times 22.3\times 273}dm^3 \)

E\(\frac{760\times 22.4\times 35.5}{750\times 308}dm^3 \)

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Question 55

neco 2003

How many Faradays of electricity are required to liberate 9g of aluminium? [Al = 27]

A0.1

B0.3

D2.7

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Question 56

neco 2003

Which metal bromide is widely used in photography?

Acalcium bromide

Bmagnesium bromide

Cpotassium bromide

Dsilver bromide

Esodium bromide

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Question 57

neco 2003

What change will occur during the electrolysis of brine using carbon electrodes?

AChlorine will be given off at the anode

BOxygen gas will be given off at the anode

CSodium will be deposited at the cathode

DThe resulting solution, after electrolysis, will be acidic.

EThe volumes of hydrogen and chlorine given off during the same time are equal

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Question 58

neco 2003

Which metal is a constituent of both bronze and solder?

Acopper

Blead

Csilver

Dtin

Ezinc

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Question 59

neco 2003

An atom of element X has an electronic configuration of \( 1s^22S^22p^63s^23p^3. \) In which group of the periodic table is X?

A\( \text{0} \)

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Question 60

neco 2003

What mass of silver is deposited when a current of 2.6 A is passed through a solution of a silver salt for 40 minutes? [Ag= 108 ; F=96500C]

A6.89g

B6.93g

C6.98g

D7.04g

E7.12g

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Question 61

neco 2003

Naturally occurring lithium consists of 90% \( ^7_3Li \text{ and 10% } ^6_3 Li. \) What is the relative atomic mass of lithium?

B6.8

C6.9

E7.1

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Question 62

neco 2003

Why does the treatment of cotton fabrics with dilute acids weaken the materials?

ACotton is hydrolysed completely to glucose

BThe fabrics are soluble in dilute acids

CThe molecular chains are partially broken

DThe molecular chain length f the fabric increases

EThe thread holding the fabric together Is completely destroyed.

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Question 63

neco 2003

An organic compound gave the following results on analysis: C = 29.3% ; H = 5.7%; Br = 65%.
What is the empirical formula of the compound? [C = 12, H = 1, Br=80]

ACH₃Br

BC₂H₅Br

CC₃H₅Br

DC₃H₇Br

EC₄H₉Br

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Question 64

neco 2003

What mass of copper is deposited when 6.5g of granulated zinc reacts with excess copper(II) tetraoxosulphate(VI) solution?

The equation for the reaction is: Zn(s) + \( CuSO_4(aq)→ ZnSO_4(aq)+ Cu(s)\)[CU= 64; Zn=65]

A3.2 g

B3.25 g

C6.4 g

D6.5 g

E64.0 g

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Question 65

neco 2003

Which element is the most electronegative?

Acalcium

Bfluorine

Ciodine

Doxygen

Esodium

View Explanation & Discuss

Question 66

neco 2003

What change will occur to the equilibrium mixture
\( 2CrO^{2-}_4(aq) + 2H^+(aq) ⇔ Cr_2O^{2-}_7(aq) + H_2O(l) \) when excess sodium hydrogen solution is added?

AA yellow precipitate of Cr(OH)₃ is formed

BAn orange precipitate of Cr(OH)₃ is formed

CThe colour changes from orange to yellow

DThe colour changes from yellow to orange

EThere is no visible reaction.

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Question 67

neco 2003

What is the IUPAC name of CH3CCI=C(CH3)2?

A2-chloro -3 methylbut -2yne

B2 -chloro -3 methylbut -2ene

C2 -chloro -3 methylbutene

D3- methyl -2-chlorobut -2-ene

E3- methyl -2. chlorobut -2 yne

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Question 68

neco 2003

Which formula is used to indicate the degree of acidity of an acid?

A\( [H^+] = ^{\text{mass of acid relative}} molecular mass of acid \)

BF = number of H+ = ions x molar mass of the acid

CKw = [H+][OH-]

DpH = - log₁₀[H+]

EpKa = -log₁₀Ka

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Question 69

neco 2003

Which compound will give propane when it Is dehy drated by an excess of hot, concentrated tetraoxosvlphate(VI) acid?

ACH₃CH₂CHO

BCH₃CH₂CH2OH

CCH₃CH₂COQH

DCH₃CH₂0CH

ECH₃CH₃OH

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Question 70

neco 2003

A calcium atom and a calcium ion have the same

Achemical properties

Belectric charge

Celectronic structure

Dnumber of electrons

Enumber of neutrons

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