Graphite is a form of carbon. Graphite can conduct electricity.
Why can graphite conduct electricity?
Delocalised electrons are between layers.
The ions can move.
Layers have weak intermolecular forces.
Strong covalent bonds are between the carbon atoms.
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Which statement about diamond is correct?
It is a hard substance with a low melting point
Each carbon atom is bonded to three others with strong covalent bonds
It has a giant structure and conducts electricity
It has a high melting point with each carbon bonded to four others
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Fullerenes are molecules made of carbon.
Fullerenes are increasingly used as catalysts due to their large surface area.
Give one other use of fullerenes.
Alloys
Lubricants
Polymers
Fuel Cells
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The diagram shows the structure of a carbon nanotube.
Which of the following is not a property of carbon nanotubes?
High tensile strength
High melting point
Poor conductor of electricity
Strong covalent bonds
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Different substances have characteristic melting and boiling points, depending on the strength of the bonds or forces holding them together.
Which explains why methane has a lower melting point than sodium chloride?
Covalent bonds are weaker than ionic bonds
Intermolecular forces are weaker than ionic bonds
Covalent bonds are stronger than ionic bonds
Intermolecular forces are stronger than ionic bonds
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1 markLook at the table of fractions from the fractional distillation of crude oil.
| Fraction | Boiling range (°C) |
| LPG | less than 25 |
| petrol | 85 – 105 |
| diesel | 150 – 290 |
| fuel oil | 290 – 380 |
| bitumen | greater than 400 |
A hydrocarbon has a boiling point which is 3.5 times the boiling point of petrol. Which fraction contains the hydrocarbon?
Bitumen
Diesel
Fuel oil
LPG
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Substance Y melts at −7 °C and boils at 59 °C.
What is the state of substance Y at room temperature?
Gas
Liquid
Plasma
Solid
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Ethanol is a liquid at room temperature. It has a low melting point and boiling point.
Why?
Ethanol is an ionic compound.
The forces of attraction between ethanol molecules are strong.
The forces of attraction between ethanol molecules are weak.
There are no forces of attraction between ethanol molecules.
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Ammonia has a simple molecular structure.
Which statement explains why ammonia has a low melting point and a low boiling point?
The covalent bonds between the atoms are strong.
The covalent bonds between the atoms are weak.
The intermolecular forces between the molecules are strong.
The intermolecular forces between the molecules are weak.
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A student tests the conductivity of an ionic compound.
Which row in the table shows the correct results?
| Solid ionic compound | Ionic compound dissolved in water | Molten ionic compound | |
| A | Conducts | Conducts | Does not conduct |
| B | Conducts | Conducts | Conducts |
| C | Does not conduct | Does not conduct | Conducts |
| D | Does not conduct | Conducts | Conducts |
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Carbon can form different allotropes.
Which of these are allotropes of carbon?
Diamond, graphite, graphene.
Diamond, granite, graphite.
Fullerene, graphene, ethene.
Granite, graphite, graphene.
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The atomic radius of a helium atom is 0.031 nm.
What is the atomic radius of a helium atom in standard form?
3.1 × 10-1
3.1 × 10-2
3.1 × 10-3
3.1 × 10-4
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Crude oil can be separated in the laboratory into fractions which have different boiling points.
Look at the table. It shows possible relationships between:
Which letter shows the correct relationship?
| Boiling point | Number of carbon atoms in the molecule | Size of intermolecular forces | |
| A | high | less than 20 | large |
| B | high | more than 50 | small |
| C | low | less than 20 | small |
| D | low | more than 50 | large |
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The melting point of bromine is −7°C.
The boiling point of bromine is 59°C.
What state would bromine be at room temperature?
Aqueous
Gas
Liquid
Solid
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Sodium chloride is often known as 'table salt'.
Which compound represents sodium chloride?
| Conducts electricity when solid | Conducts electricity when molten | State at room temperature and pressure | Can be bent or shaped | |
| A | Yes | Yes | Solid | Yes |
| B | No | No | Solid | No |
| C | No | Yes | Solid | No |
| D | No | No | Solid | Yes |
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Carbon dioxide exists as a simple molecule.
Why do simple molecules have low boiling points?
Simple molecules have weak covalent bonds between atoms.
Simple molecules have weak intermolecular forces between atoms.
Simple molecules have weak ionic bonds between the molecules.
Simple molecules have weak intermolecular forces between the molecules.
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Which row explains how the structure of graphene is different from the structure of graphite?
|
Graphene |
Graphite |
|
|
A |
3 covalent bonds to each carbon atom |
4 covalent bonds to each carbon atom |
|
B |
covalent bonds in 3D |
covalent bonds in one 2D plane |
|
C |
intermolecular forces |
no intermolecular forces |
|
D |
one layer |
many layers |
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