IGCSEChemistry: Double ScienceEdexcelTopic Questions2. Inorganic Chemistry2.2 Group 7 (Halogens)

Group 7 (Halogens) (Edexcel IGCSE Chemistry: Double Science)

Topic Questions

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1a1 mark

Astatine, bromine, chlorine, fluorine and iodine are all halogens. They are found in Group 7 of the Periodic Table.

a)
Predict which halogen has the lightest colour.
(1) 

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1b1 mark
b)
Name a halogen that is a solid at room temperature.
(1) 

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1c3 marks
c)
Bromine can be obtained from the bromide ions in sea water. Chlorine is bubbled into sea water. The chlorine oxidises the bromide ions to bromine atoms. The bromine atoms then form bromine molecules.

i)
Complete the equation to show how bromine atoms are formed from bromide ions.

Cl2 + ..................... Br− → 2Cl− + ..................... Br
(1)
ii)
State why this reaction is described as the oxidation of bromide ions.
(1)
iii)
Write an equation to show how bromine atoms form bromine molecules.
(1)

 

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1d2 marks
d)
Boron and fluorine form a covalent compound that has the molecular formula BF3
Draw a dot-and-cross diagram to show the arrangement of the outer electrons in a molecule of BF3
Use crosses (×) to represent the outer electrons of boron. Use dots (•) to represent the outer electrons of fluorine.
(2) 

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1a3 marks
a)
This question is about some of the halogens and their compounds.

i)
Which element is a liquid at room temperature?
(1)
  ☐ A astatine
  ☐ B bromine
  ☐ C chlorine
  ☐ D iodine

 

ii)
Which element has the palest colour?
(1)
 
  ☐ A astatine
  ☐ B bromine
  ☐ C chlorine
  ☐ D iodine

 

iii)
Which element is the least reactive?
(1)
  ☐ A astatine
  ☐ B bromine
  ☐ C chlorine
  ☐ D iodine

 

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1b4 marks
b)
A teacher uses displacement reactions to demonstrate the reactivities of some halogens.
She adds solutions of chlorine, bromine and iodine separately to three different sodium halide solutions.

The table shows some of the teacher’s results.

  sodium chloride sodium  bromide sodium  iodide
 chlorine solution  not done  solution turns orange  
 bromine solution  solution stays orange  not done  solution turns brown
 iodine solution    solution stays brown  not done

A change in colour of the solution indicates that a reaction has occurred.

i)
Complete the table by predicting the missing results.

[2]

ii)
State why the teacher does not add bromine solution to sodium bromide solution.

[1]

iii)
The word equation for the reaction of bromine with sodium iodide is

bromine + sodium iodide → iodine + sodium bromide

Write a chemical equation for this reaction.

[1]

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1c6 marks
c)
A technician sees an unlabelled bottle containing a liquid.

He knows that the liquid is a solution of one of these compounds.

  • copper(II) chloride
  • copper(II) bromide
  • iron(II) chloride
  • iron(II) bromide
Describe chemical tests that the technician could use to identify the compound in the solution.

[6]

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21 mark

Which element in Group 7 is a solid at room temperature?

(1)

  ☐ A fluorine
  ☐ B chlorine
  ☐ C bromine
  ☐ D iodine

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3a2 marks

This question is about the halogens.

a)
The table gives some information about the halogens.

Complete the table by predicting the physical state of astatine at room temperature and the colour of astatine.

(2)

Halogen Physical state at room temperature Colour
 fluorine gas yellow
 chlorine gas pale green
 bromine liquid red-brown
 iodine solid grey
 astatine    

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3b
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b)
Bromine has two isotopes with mass numbers 79 and 81

i)
The relative percentages of each isotope in a sample of bromine are

bromine-79 = 51.0%                   bromine-81 = 49.0%

Calculate the relative atomic mass of this sample of bromine.

Give your answer to one decimal place.

(3)


relative atomic mass = ..............................................................

ii)
Give a reason why both isotopes of bromine have the same chemical properties.
(1)

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3c6 marks
c)
A student investigates the reactivity of some halogens.

She uses these solutions of halogens and their halides.
  • bromine, chlorine and iodine
  • sodium bromide, sodium chloride and sodium iodide
She adds each halogen solution to each halide solution.

The table shows her results.

  Sodium bromide Sodium chloride Sodium iodide
 Bromine no reaction no reaction reaction occurs
 Chlorine reaction occurs no reaction reaction occurs
 Iodine no reaction no reaction no reaction

i)
Explain how these results show the order of reactivity of bromine, chlorine and iodine.

(3)

ii)
Suggest why the student does not need to add bromine solution to sodium bromide solution.

(1)

iii)
The ionic equation for the reaction between bromine and sodium iodide is

Br2 (aq) + 2I− (aq) → I2 (aq) + 2Br− (aq)

Explain why this is a redox reaction.

(2)

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41 mark

This table gives information about some of the halogens.

Halogen Physical state at room temperature Colour
fluorine gas  
chlorine   pale green
bromine liquid red-brown

What is the correct missing physical state and colour?

(1)

      Physical state at room temperature Colour
  ☐ A gas colourless
  ☐ B liquid colourless
  ☐ C gas pale yellow
  ☐ D liquid pale yellow

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5a1 mark

The Group 7 elements are called halogens.
Halogens form compounds called halides.
Three of the halogens are represented by the formulae X2 , Y2 and Z2
Solutions of these halogens are added separately to solutions of sodium halides, NaX, NaY and NaZ.
The table shows whether or not a reaction occurs.

  X2 Y2 Z2
NaX no yes yes
NaY no no yes
NaZ no no no

a)
Use the information in the table to deduce the order of reactivity of the halogens X2 , Y2 and Z2
 

most reactive ...................................
          ....................................

least reactive ....................................

(1)

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5b1 mark
b)
An aqueous solution of halogen Y2 is orange.
This solution is decolourised when it reacts with an alkene.
Deduce the identity of halogen Y2.
(1)

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5c4 marks
c)
The table shows some physical properties of the halogens.

i)
Complete the table by predicting a boiling point for chlorine, the state of fluorine at room temperature and the colour of astatine.
Halogen Boiling point in °C State at room temperature Colour
 fluorine -188   yellow
 chlorine   gas green
 bromine 59 liquid red-brown
 iodine sublimes solid grey
 astatine 337 solid  

(3)

ii)
Why do the halogens have similar chemical properties?
(1)
 
  ☐ A they are non-metals
  ☐ B they are molecules
  ☐ C they have the same number of outer shell electrons
  ☐ D they are in the same period of the Periodic Table

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5d3 marks
d)
A teacher uses this apparatus to demonstrate the reaction between chlorine gas and iron wool. The teacher does the reaction in a fume cupboard.

iron-wool-and-chlorine-reaction-diagram

i)
Suggest why the teacher does the reaction in a fume cupboard.

(1)

ii)
The product of the reaction between iron and chlorine is iron(III) chloride.
The ions in iron(III) chloride are Fe3+ and Cl−.
Use this information to give the chemical equation for this reaction.
(2)

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61 mark

Astatine is found below iodine in Group 7 of the Periodic Table.

What is its formula and state at room temperature?

(1)

      Formula State at room temperature
  ☐ A At gas
  ☐ B At solid
  ☐ C At2 liquid
  ☐ D At2 solid

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71 mark

The reaction between aqueous chlorine and aqueous potassium bromide results in the formation of an orange solution.

Which is the correct statement about this reaction?

(1)

  ☐ A Bromine is more reactive than chlorine
  ☐ B Potassium chloride is responsible for the orange colour
  ☐ C Chlorine displaces bromine from potassium bromide
  ☐ D Bromide ions gain electrons from chlorine

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8a3 marks

This question is about elements in Group 7 and their compounds.

The table gives information about some of these elements.

Element Symbol Melting point Boiling point
in °C		 Colour at room
temperature (20 °C)
fluorine F –220 –188  
chlorine Cl –101 –35 pale green
bromine Br –7 59 red-brown
iodine I 114 184 grey

a) i)
Predict the colour of fluorine at room temperature.
(1)
ii)
How many of the elements in the table are liquids at room temperature (20 °C)?
(1)
  ☐ A 0
  ☐ B 1
  ☐ C 2
  ☐ D 3

iii)
The element astatine is below iodine in Group 7. Predict the formula of a molecule of astatine.
(1)

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8b1 mark
b)
Elements in Group 7 react with elements in Group 1 to form ionic compounds.

Which pair of ions both have the electronic configuration 2.8.8?
(1)
  ☐ A Li+ and Cl
  ☐ B K+ and F–
  ☐ C Li+ and F–
  ☐ D K+ and Cl–

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91 mark

Bromine water is an aqueous solution of bromine which is orange in colour.

What would be seen if bromine water was added to the test tubes in the diagram?

(1)

2-2-q5-edexcel-igcse-chemistry

                           

      Test tube 1 Test tube 2 Test tube 3
  ☐ A solution stays orange  solution turns brown  solution turns brown
  ☐ B solution turns pale green  solution stays orange  solution turns colourless
  ☐ C  solution stays orange solution stays orange  solution turns brown
  ☐ D solution turns colourless  solution turns colourless solution turns brown

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10a2 marks

The table gives some information about the halogens, chlorine, bromine and iodine.

Halogen

Physical state at room temperature 

Colour
chlorine  gas  pale green
bromine    red-brown
iodine  solid  

a)
Complete the table.
(2)

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10b
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b)
Chlorine has two isotopes of mass numbers 35 and 37.
The relative percentage of each isotope in a sample of chlorine is

chlorine-35 77.78%    chlorine-37 22.22%

Calculate the relative atomic mass of this sample of chlorine. Give your answer to one decimal place.

Relative atomic mass = .........................

(3)

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10c4 marks
c)
A student is given an aqueous solution of chlorine and an aqueous solution of potassium bromide.
Explain how he can use these two solutions to compare the reactivity of chlorine with the reactivity of bromine.
(4)

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