Exam code: 9701
The halogens exist as diatomic molecules, X2.
Descending through Group 17 from chlorine to iodine the boiling points of the elements increase.
Which statement explains this trend?
The permanent dipole in the X2 molecule increases down the group.
The X–X bond strength increases down the group.
The electronegativity of X decreases down the group.
The number of electrons in each X2 molecule increases down the group.
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Which row describes the trends in the strengths of the forces between molecules and the bonds within molecules, going down Group 17 from chlorine to iodine?
strength of van der Waals' forces | strength of covalent bonds | |
|---|---|---|
A | decrease | decrease |
B | decrease | increase |
C | increase | decrease |
D | increase | increase |
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Which property is greater for iodine than for chlorine?
oxidising ability of the element
solubility of the silver halide in NH3 (aq)
strength of van der Waals' forces between the molecules of the element
thermal stability of the hydrogen halide
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Which row correctly describes the trends in the properties of the hydrogen halides from HCl to HI?
bond length | ease of oxidation | thermal stability | |
|---|---|---|---|
A | decreases | decreases | increases |
B | decreases | increases | decreases |
C | increases | decreases | increases |
D | increases | increases | decreases |
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The table shows some properties of three halogens at room temperature and pressure (r.t.p.).
halogen | colour at r.t.p. | physical state at r.t.p. | boiling point / K |
|---|---|---|---|
chlorine | pale green | gas | 239 |
bromine | X | Y | 332 |
iodine | Z | solid | 457 |
Which row identifies X, Y and Z?
X | Y | Z | |
|---|---|---|---|
A | orange-brown | gas | purple |
B | pale yellow | liquid | purple |
C | red-brown | liquid | grey-black |
D | red-brown | solid | grey-black |
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The following report appeared in a newspaper.
Barrels of bromine broke open after a vehicle collision on the motorway. Traffic was diverted as purple gaseous bromine drifted over the surface of the road (as bromine is more dense than air), causing irritation to drivers' eyes. Firefighters sprayed water over the scene of the accident, dissolving the bromine and washing it away. |
|---|
Which property described in the report is chemically incorrect?
Bromine is denser than air.
Bromine does not vaporise readily
Bromine is purple in the gaseous state.
Bromine vaporises readily.
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A molecule of chlorine has a relative molecular mass of 72.
Which property is the same for both atoms in this molecule?
atomic radius
nucleon number
number of neutrons
relative isotopic mass
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Which graph correctly shows a property of the elements in Group 17 from fluorine to iodine plotted against proton number?
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Which statement about the elements in Group 17 and their compounds is not correct?
Astatine has a lower first ionisation energy than iodine.
CH3I produces a silver halide precipitate with aqueous silver nitrate in ethanol faster than CH3Cl or CH3Br.
Fluorine is the weakest reducing agent of the Group 17 elements.
The bond dissociation energy of the hydrogen halides increases from HCl to HI.
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Which statement explains why HBr (aq) is a stronger acid than HF (aq)?
HF (aq) dissociates more readily than HBr (aq) when dissolved in solution.
HF (aq) releases more H+ ions than HBr (aq).
The H–Br bond has a higher bond dissociation energy than the H–F bond.
The H–F bond is stronger than the H–Br bond and does not break as easily.
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Shown on the graph are the relative values of the first ionisation energies of four elements that have consecutive atomic numbers. One of the elements reacts with hydrogen to form a covalent compound with formula HX.
Which element could be X?
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