NECO SSCE - Chemistry - 2003

Separation Of Mixtures And Purification Of Chemical Substances

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Pergunta 5 Relatório

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]

CH₃Br

C₂H₅Br

C₃H₅Br

C₃H₇Br

C₄H₉Br

Detalhes da Resposta

Read lesson note on Organic Compounds (JAMB)

Organic Compounds

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Pergunta 6 Relatório

Which separation technique is routinely applied in the petroleum industry?

chromatography

distillation

evaporation

fractional crystallization

fractional distillation

Detalhes da Resposta

Read lesson note on Separation Of Mixtures And Purification Of Chemical Substances (JAMB)

Separation Of Mixtures And Purification Of Chemical Substances

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Pergunta 7 Relatório

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

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

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

Kw = [H+][OH-]

pH = - log₁₀[H+]

pKa = -log₁₀Ka

Detalhes da Resposta

Read lesson note on Acids, Bases And Salts (Ghana Only) (WAEC)

Read lesson note on Periodic Chemistry (Ghana Only) (WAEC)

Periodic Chemistry (Ghana Only)

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Pergunta 8 Relatório

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

6.8

6.9

7.1

Detalhes da Resposta

Read lesson note on Kinetic Theory Of Matter And Gas Laws (JAMB)

Read lesson note on Atomic Structure And Bonding (JAMB)

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Pergunta 9 Relatório

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]

3.2 g

3.25 g

6.4 g

6.5 g

64.0 g

Detalhes da Resposta

Read lesson note on Stoichiometry And Chemical Reactions (WAEC)

Stoichiometry And Chemical Reactions

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Pergunta 10 Relatório

What is the concentration (in mol dm³) of a solution containing 28 g of potassium hydroxide per 100 cm³ of solution? (K=39; H=1; 0=16)

0.01

0.05

0.1

0.5

2.8

Detalhes da Resposta

Read lesson note on Kinetic Theory Of Matter And Gas Laws (JAMB)

Read lesson note on Acids, Bases And Salts (Ghana Only) (WAEC)

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Pergunta 11 Relatório

Which metal bromide is widely used in photography?

calcium bromide

magnesium bromide

potassium bromide

silver bromide

sodium bromide

Detalhes da Resposta

Read lesson note on Metals And Their Compounds (JAMB)

Metals And Their Compounds

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Pergunta 12 Relatório

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]

\( ^{\text{760 x 22.4 x 308}} \text{750 x 273x 35.5} dm^3 \)

\( ^{\text{760 x 22.4 x 308}} \text{750 x 273}^x dm^3 \)

\( ^{\text{750 x 22.4 x 35.5}} \text{760 x 273dm3} \)

\( ^{\text{760 x 22.4 x 35.5}} \text{750x22.3x273} \)

\( ^{\text{760 x 22.4 x 35.5}} \text{750 x 308dm3} \)

Detalhes da Resposta

Read lesson note on Kinetic Theory Of Matter And Gas Laws (JAMB)

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Pergunta 13 Relatório

The pH of water is 7.

What is the pH of orange juice?

above 10

below 2

between 5.5 and 6.5

between 7.5 and 8.5

Detalhes da Resposta

Read lesson note on Acids, Bases And Salts (Ghana Only) (WAEC)

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Pergunta 14 Relatório

A calcium atom and a calcium ion have the same

chemical properties

electric charge

electronic structure

number of electrons

number of neutrons

Detalhes da Resposta

Read lesson note on Atomic Structure And Bonding (JAMB)

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Pergunta 15 Relatório

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

distillation

electrochemical

electrolysis

neutralization

reduction

Detalhes da Resposta

Read lesson note on Electrolysis (JAMB)

Electrolysis

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Pergunta 16 Relatório

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

Cotton is hydrolysed completely to glucose

The fabrics are soluble in dilute acids

The molecular chains are partially broken

The molecular chain length f the fabric increases

The thread holding the fabric together Is completely destroyed.

Detalhes da Resposta

Read lesson note on Acids, Bases And Salts (JAMB)

Read lesson note on Oxidation And Reduction (JAMB)

Acids, Bases And Salts

Oxidation And Reduction

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Pergunta 17 Relatório

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

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

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

water has a higher lattice energy than ethanol.

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

water is a better solvent than ethanol.

Detalhes da Resposta

Read lesson note on Chemical Bonds (Nigeria Only) (WAEC)

Read lesson note on Energy And Energy Changes (WAEC)

Chemical Bonds (Nigeria Only)

Energy And Energy Changes

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Pergunta 18 Relatório

What is formed when starch is completely hydrolysed?

fructose

glucose

lactose

maltose

sucrose

Detalhes da Resposta

Read lesson note on Kinetic Theory Of Matter And Gas Laws (JAMB)

Read lesson note on Oxidation And Reduction (JAMB)

Read lesson note on Acids, Bases And Salts (Ghana Only) (WAEC)

Oxidation And Reduction

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Pergunta 19 Relatório

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

46 protons and 119 neutrons

92 protons and 92 neutrons

92 protons and 146 neutrons

92 protons and 238 neutrons

Detalhes da Resposta

Read lesson note on Atomic Structure And Bonding (JAMB)

Read lesson note on Chemical Equilibra (JAMB)

Chemical Equilibra

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Pergunta 20 Relatório

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

Chlorine will be given off at the cathode

Oxygen gas will be given off at the anode

Sodium will be deposited at the cathode

The resulting solution, after electrolysis, will be acidic.

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

Detalhes da Resposta

Read lesson note on Electrolysis (JAMB)

Read lesson note on Acids, Bases And Salts (Ghana Only) (WAEC)

Electrolysis

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Pergunta 21 Relatório

Why is tetraoxosulphate(VI) acid NOT used for making carbon dioxide from calcium carbonate? It is

a dehydrating agent

a strong acid

an oxidising agent

dibasic

forms insoluble calcium tetraoxosulphate(Vl)

Detalhes da Resposta

Read lesson note on Acids, Bases And Salts (JAMB)

Acids, Bases And Salts

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Pergunta 22 Relatório

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?

A yellow precipitate of Cr(OH)₃ is formed

An orange precipitate of Cr(OH)₃ is formed

The colour changes from orange to yellow

The colour changes from yellow to orange

There is no visible reaction.

Detalhes da Resposta

Read lesson note on Chemical Kinetics And Equilibrium Systems (Ghana Only) (WAEC)

Read lesson note on Structure Of The Atom (WAEC)

Chemical Kinetics And Equilibrium Systems (Ghana Only)

Structure Of The Atom

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Pergunta 23 Relatório

Small amounts of compounds of transition metals are sometimes added to glass during manufacture in order to make the glass

acquire certain colours

easier to melt

easier to mould

little brittle

more transparent

Detalhes da Resposta

Read lesson note on Chemical Combination (JAMB)

Chemical Combination

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Pergunta 24 Relatório

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

CH₃CH₂CHO

CH₃CH₂CH2OH

CH₃CH₂COQH

CH₃CH₂0CH

CH₃CH₃OH

Detalhes da Resposta

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Pergunta 25 Relatório

Which hydrocarbon does NOT exhibit structural isomerism?

C₃H₆

C₄H₆

C₄H₈

C₄H₁₀

C₅H₁₂

Detalhes da Resposta

Read lesson note on Chemistry Of Carbon Compounds (Nigeria Only) (WAEC)

Chemistry Of Carbon Compounds (Nigeria Only)

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Pergunta 26 Relatório

Which metal is extracted from bauxite?

aluminium

calcium

copper

magnesium

tin

Detalhes da Resposta

Read lesson note on Metals And Their Compounds (JAMB)

Metals And Their Compounds

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Pergunta 27 Relatório

Which element is the most electronegative?

calcium

fluorine

iodine

oxygen

sodium

Detalhes da Resposta

Read lesson note on Atomic Structure And Bonding (JAMB)

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Pergunta 28 Relatório

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]

6.89g

6.93g

6.98g

7.04g

7.12g

Detalhes da Resposta

Read lesson note on Chemical Kinetics And Equilibrium System (Nigeria Only) (WAEC)

Read lesson note on Electrolysis (JAMB)

Chemical Kinetics And Equilibrium System (Nigeria Only)

Electrolysis

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Pergunta 29 Relatório

The reaction C₂H₆ → C₂H + H₂ is known as

dehydration

dehydrogenation

displacement

hydrogenation

reduction

Detalhes da Resposta

Read lesson note on Chemistry Of Carbon Compounds (Nigeria Only) (WAEC)

Chemistry Of Carbon Compounds (Nigeria Only)

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Pergunta 30 Relatório

Which metal is a constituent of both bronze and solder?

copper

lead

silver

tin

zinc

Detalhes da Resposta

Read lesson note on Metals And Their Compounds (JAMB)

Metals And Their Compounds

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Pergunta 31 Relatório

Which statement is NOT true about the composition of starch?

It contains only the atoms of carbon, hydrogen oxygen

It is a polysaccharide

Its empirical formula is C₂H₂0.

It is made from the monomerC₆H₁₂O₆.

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

Detalhes da Resposta

Read lesson note on Chemistry Of Carbon Compounds (Nigeria Only) (WAEC)

Chemistry Of Carbon Compounds (Nigeria Only)

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Pergunta 32 Relatório

An atom of element X has an electronic configuration of \( 1s^22p^33s^23p^2. \) In which group of the periodic table is X?

\( \text{0} \)

Detalhes da Resposta

Read lesson note on Atomic Structure And Bonding (JAMB)