Diamond, graphite and silicon dioxide all have giant covalent structures.
The diagram shows the structures of these three substances.
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[1]
[2]
[2]
[6]
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This question is about substances with covalent bonds.
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| Structure A | Graphite | C60 Fullerene |
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Carbon dioxide contains covalent bonds.
The covalent bonds in a molecule of carbon dioxide can be represented by a dot-and-cross diagram.
Which is the correct dot-and-cross diagram for carbon dioxide?
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| ☐ | A |  |
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| ☐ | B |  |
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| ☐ | C |  |
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| ☐ | D |  |
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(3)
(2)
(1)
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This question is about carbon and its compounds.
(2)
(2)
(2)
(5)
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Silicon dioxide, SiO2, and silicon(IV) chloride, SiCl4, are both covalently bonded compounds.
The table below shows the melting point and boiling point of these compounds.
| Compound | Melting point / o C | Boiling point / o C |
| Silicon dioxide | 1710 | 2230 |
| Silicon(IV) chloride | -69 | 58 |
Which statement is not correct about the two compounds?
(1)
| ☐ | A | at room temperature silicon dioxide is a solid and silicon(IV) chloride is a liquid | |
| ☐ | B | silicon dioxide has a giant covalent structure | |
| ☐ | C | silicon(IV) chloride has a lower melting point as it has fewer covalent bonds to overcome | |
| ☐ | D | silicon(IV) chloride has a simple molecular structure |
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This question is about some compounds of the elements in Group 4 of the Periodic Table.
(1)
| ☐ | A | 1 | |
| ☐ | B | 5 | |
| ☐ | C | 7 | |
| ☐ | D | 9 |
| ☐ | A | acids contain OH− ions | |
| ☐ | B | acids are electron donors | |
| ☐ | C | acids are proton acceptors | |
| ☐ | D | acids are proton donors |
PbCO3 → .............................................. + ..............................................
| Compound | Melting point in °C | Boiling point in °C | Physical state at room temperature |
| SiO2 | 1710 | 2230 | solid |
| SiCl4 | −69 | 58 |
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#The diagram shows the structures of three substances that have giant covalent structures.
Which does not provide the correct explanation of the property of a substance?
| Substance | Property | Explanation | |
| A | graphite | conducts electricity | its ions are free to move through the layers |
| B | diamond | hard | each carbon atom is covalently bonded to four other carbon atoms |
| C | silicon dioxide | high melting point | it has many strong covalent bonds which require a large amount of energy to break |
| D | graphite | soft | its layers can slide over each other |
(1)
| ☐ | A | ||
| ☐ | B | ||
| ☐ | C | ||
| ☐ | D |
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Ammonia, NH3, is a small covalent molecule.
How many non-bonding, outer-shell electrons are present in one molecule of ammonia?
(1)
| ☐ | A | 0 | |
| ☐ | B | 2 | |
| ☐ | C | 5 | |
| ☐ | D | 6 |
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2 marksHalon 1301 is a compound used in some fire extinguishers.
Halon 1301 has the percentage composition by mass of
C 8.05% Br 53.69% F 38.26%
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