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Chemistry Past Questions

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38 questions JAMB 2505 WAEC 1623 NECO 168 CUSTOM 10

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38 questions

Question 1 of 18 38 total questions

Question 11

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 12

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 13

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 14

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 15

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 16

neco 2003

Which element is the most electronegative?

Acalcium

Bfluorine

Ciodine

Doxygen

Esodium

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Question 17

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 18

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 19

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 20

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 21

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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Question 22

neco 2003

Which is NOT a synthetic polymer?

Anylon

BOrion

CPerspex

Dpolystyrene

Ewool

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Question 23

neco 2003

The reaction C₂H₆ → C₂H + H₂ is known as

Adehydration

Bdehydrogenation

Cdisplacement

Dhydrogenation

Ereduction

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Question 24

neco 2003

The boiling point of water is higher than the boiling point of ethanol because

Athe bonding in water is electrovalent (ionic) whereas the bonding in ethanol is convalent

Bthe hydrogen bonding between water molecules is stronger than the hydrogen bonding between ethanol molecules

Cwater has a higher lattice energy than ethanol.

Dwater has hydrogen bonding between its molecules but ethanol has no hydrogen bonging between its molecules;

Ewater is a better solvent than ethanol.

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Question 25

neco 2003

B is an isotope of the element \(^{238} _{92}Ur\). The isotope B has

A46 protons and 119 neutrons

B92 protons and 92 neutrons

C92 protons and 146 neutrons

D92 protons and 238 neutrons

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Question 26

neco 2003

The number of hydrogen ions in 1.0dm\(^3\) of a 0.25 mole tetraoxosulphate(Vl) acid solution is
[Avogadro c x 10\(^{23}\)]

A1.45x10²³

B1.50 x l0²³

C3.00x10²³

D3.15x10²³

E6.00x10²³

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Question 27

neco 2003

Chlorine is used in water purification because it

Ableaches impurities in the water

Bdecolorizes water

Cdestroys bacteria

Dis extremely soluble in water

Eis pleasant tasting

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Question 28

neco 2003

Which statement is NOT true about the composition of starch?

AIt contains only the atoms of carbon, hydrogen oxygen

BIt is a polysaccharide

CIts empirical formula is C₂H₂0.

DIt is made from the monomerC₆H₁₂O₆.

EThe hydrogen and oxygen atoms are in the ratio 2:1.

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