OCR A Level Chemistry

Topic Questions

2.5 The Shapes of Simple Molecules & Ions

11 mark

Which molecule is not planar?

  • C2H4

  • C2H6

  • H2CO

  • HCN

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21 mark

Which element has induced dipole–dipole interactions (London forces) in its solid lattice?

  • Boron

  • Magnesium 

  • Silicon 

  • Sulfur

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31 mark

What is the shape around the carbon atoms in graphene?

  • Linear

  • Pyramidal 

  • Tetrahedral 

  • Trigonal planar

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41 mark

A ‘dot-and-cross’ diagram for nitrogen trichloride, NCl3, is shown below.

61b0d7c4-0cc6-46ec-b2de-47b1df2626ff

Which row shows the correct shape and bond angle in a molecule of NCl3?

  Name of shape Bond angle 
A Pyramidal 104.5 °
B Pyramidal 107 °
C Tetrahedral 107 °
D Trigonal planar 120 °

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51 mark

Which molecule is non-polar?

  • SF6

  • H2O

  • PF3

  • NH3

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61 mark

Which substance contains hydrogen bonding in the liquid state?

  • CH3(CH2)4CH3

  • CH3(CH2)3CHFCH3

  • CH3(CH2)3COCH3

  • CH3(CH2)3CH(OH)CH3

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71 mark

The boiling point of hydrogen bromide is –67 °C.

The boiling point of hydrogen iodide is –34 °C.

The different boiling points can be explained in terms of the strength of bonds or interactions.

Which bonds or interactions are responsible for the higher boiling point of hydrogen iodide?

  • Covalent bonds

  • Hydrogen bonds

  • Permanent dipole–dipole interactions

  • Induced dipole–dipole interactions

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81 mark

What is the correct bond angle in a trigonal planar molecule?

  • 107°

  • 120°

  • 180°

  • 109.5°

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91 mark

Which of the following is correct?

 

Shape of SF6 molecule

Bond angle in SF6 molecule

A

Octahedral

90°

B

Square planar

90°

C

Trigonal bipyramidal 

120°

D

Tetrahedral 

109.5°

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101 mark

Which statement is correct for a molecule of CCl4?

 

Total number of valence electrons

Number of bonding pairs 

Number of lone pairs

A

30

4

2

B

32

4

0

C

34

4

1

D

16

4

0

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11 mark

Which compound has non-polar molecules?

  • E-1,2-dichlorobut-2-ene

  • E-2,3-dichlorobut-2-ene

  • Z-2,3-dichlorobut-2-ene

  • Z-1,4-dichlorobut-2-ene

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21 mark

Four atoms, 1-4, are labelled in the structure below

aspirin---identify-the-atom2

Which atom has a v-shaped arrangement of bonds around it?

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31 mark

Which row has the correct shape, bond angle and explanation for the following molecules?

 

Molecule

Shape

Bond angle

Explanation

 

A

 

Ethanoic acid

Pyramidal around the carbonyl carbon

 

107o

The carbon atom is sp2 hybridised so the double bond repels more than the single bonds

 

B

 

[Cu(NH3)4(H2O)2]2+

 

Octahedral

 

90o

The eight bonding pairs will repel each other equally

 

C

 

Cisplatin

 

Square planar

 

109.5o

Minimises the repulsion between the electrons in the d orbitals

 

 

D

 

 

Sulfur dioxide

 

 

Bent

 

 

119o

Lone pairs repel more than bonding pairs due to a higher concentration of the electron charge cloud

 

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41 mark

Which of the following statements is/are correct?

  1. Bromoethane is more reactive than chloroethane because bromine is less electronegative than chlorine.
  2. The C-Br bond in bromoethane requires more energy to break than the C-Cl bond in chloroethane due to the C-Br bond being more polar.
  3. The C-Br bond in bromoethane is stronger than the C-Cl bond in chloroethane due to bromine having an increased nuclear charge.
  • 1, 2 and 3

  • Only 1 and 2

  • Only 2 and 3

  • Only 1

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51 mark

This question is about butane, propanone and the amino acid glycine (R group -H).

Which of the following statements is/are correct?

  1. Butane and propanone have the same number of electrons so their induced dipole-dipole intermolecular forces are the same.
  2. Only glycine will dissolve in water because it has hydrogen bonding.
  3. Within a protein, glycine has one place in which a hydrogen bond could form.
  • 1, 2 and 3

  • Only 1 and 2

  • Only 2 and 3

  • Only 1

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11 mark

What is the correct shape and bond angle of the phosphonium ion, PH4+

  • Tetrahedral and 109.5°

  • Square planar and 90°

  • V-shaped and 105°

  • Tetrahedral and 107°

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21 mark

Which molecule is nonpolar?

  • CH3CHICH3  

  • BF3

  • BrF5

  • CH3CHO

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31 mark

Which one of these species has a bond angle of 120°?

  • H3O+  

  • TlBr32-

  • BCl3

  • NH3

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41 mark

What is the strongest type of intermolecular force exhibited in the amino acid molecule serine?

Serine

Serine

  • London dispersion forces 

  • Permanent dipole-dipole forces

  • Hydrogen bonding

  • Covalent bonding

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51 mark

Which organic compound has the highest boiling point?

  • Butan-1-ol

  • Butane

  • 1-chlorobutane

  • Propane

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61 mark

Which molecule has the lowest boiling point?

  • CH3CH2CHO

  • CH3CH2CH2Cl

  • CH3CH2CH3

  • CH3CH2COOH

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71 mark

Which statement explains why water is more dense than ice?

  • Ice contains hydrogen bonds, but water does not contain hydrogen bonds

  • Hydrogen bonds are stronger in water than in ice

  • Hydrogen bonds hold H2O molecules closer together in water 

  • Ice is a solid and water is a liquid 

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81 mark

Which statement explains why hexane has a higher boiling point than 2,2-dimethylbutane?

  • Hexane has a higher Mr than 2,2-dimethylbutane

  • 2,2-dimethylbutane has a lower boiling point as it is a branched molecule 

  • 2,2-dimethylbutane only contains London dispersion forces 

  • Hexane contains permanent dipole dipole forces

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91 mark

Which element has induced dipole dipole interactions (London dispersion forces) in its solid lattice?

  • Sodium 

  • Diamond

  • Phosphorus 

  • Beryllium 

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