11 mark
Which of the following compounds are formed by covalent bonding?
| 1 | Potassium fluoride |
| 2 | Propane |
| 3 | Carbon dioxide |
| 4 | Lithium bromide |
2 and 3
2 and 4
1, 2 and 3
1 and 4
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Simple Molecules & Covalent Bonds (Cambridge O Level Chemistry)
Exam Questions
2 hours31 questions21 mark
Which row correctly describes a simple covalent compound?
| low melting point | high boiling point | |
| A | format('truetype')%3Bfont-weight%3Anormal%3Bfont-style%3Anormal%3B%7D%3C%2Fstyle%3E%3C%2Fdefs%3E%3Ctext%20font-family%3D%22stixf5dffc111454b227fbcdf36178d%22%20font-size%3D%2218%22%20text-anchor%3D%22middle%22%20x%3D%229.5%22%20y%3D%2218%22%3E%26%23x2713%3B%3C%2Ftext%3E%3C%2Fsvg%3E) |
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| B | format('truetype')%3Bfont-weight%3Anormal%3Bfont-style%3Anormal%3B%7D%3C%2Fstyle%3E%3C%2Fdefs%3E%3Ctext%20font-family%3D%22math13b8a614226a953a8cd9526fca6%22%20font-size%3D%2216%22%20text-anchor%3D%22middle%22%20x%3D%228.5%22%20y%3D%2216%22%3E%26%23xD7%3B%3C%2Ftext%3E%3C%2Fsvg%3E) |
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| C | |
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| D | |
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31 mark
Which statement about bonding is not correct?
Covalent bonding involves non metal elements.
Covalent bonding involves electron sharing.
Covalent bonding involves electron transfer.
Covalent bonding does not involve metal elements.
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41 mark
Ammonia is a covalent compound consisting of one nitrogen atom bonded to three hydrogen atoms.
Which statement is correct for a molecule of ammonia?
The number of shared pairs of electrons is five
The number of shared pairs of electrons is three
There are single covalent bonds between the hydrogen atoms.
Each hydrogen atom donates one pair of electrons to the central nitrogen atom.
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51 mark
Extended Only
The structure of propane is shown below
Which correctly explains why propane can not conduct electricity?
There are weak intermolecular forces between molecules of propane
The covalent bonds in propane are strong
There are no free electrons able to move and carry a charge
Propane has a low boiling point
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11 mark
Atoms P and Q have electronic structures as shown in the diagram. They react together to form a covalent compound.
What is the formula of the compound?
P2Q3
P3Q
P3Q2
PQ4
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21 mark
The atom of element Z has 6 electrons in its outer shell. How would this element react?
It shares two electrons with four from another atom to form two covalent bonds
It shares four electrons with four from another atom to form four covalent bonds
It shares four electrons with two from another atom to form two covalent bonds
It shares two electrons with two from another atom to form two covalent bonds
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31 mark
CH4, H2O and HCl are covalent compounds.
Which atoms in these compounds do not use all of their outer shell electrons in bonding?
C and O
C and H
Cl and O
Cl and C
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41 mark
The electronic configurations of four different atoms are shown below.
Which atoms form covalent compounds?
W and X
W, X and Y
W and Z
X, Y and Z
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51 mark
Which of the following molecules contains only single covalent bonds?
N2
F2
O2
CO2
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61 mark
What is a covalent bond?
a pair of electrons shared by two non-metallic atoms
electrons being shared by a lattice of positively charged ions
elements losing electrons to achieve a noble gas structure
oppositely charged particles strongly attracting each other
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71 mark
Ethane, C2H6, and ammonia, NH3, are covalent compounds.
The dot-and-cross diagrams of these compounds are shown.
Which statements are correct?
| 1 | A molecule of ethane contains twice as many hydrogen atoms as a molecule of ammonia. |
| 2 | An unreacted nitrogen atom has five outer electrons. |
| 3 | In a molecule of ethane, the bond between the carbon atoms is formed by sharing two electrons, one from each carbon atom. |
1, 2 and 3
1 and 2 only
1 and 3 only
2 and 3 only
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11 mark
Carbon dioxide is a simple molecular substance in which the molecules are formed by covalent bonding between one carbon atom and two oxygen atoms.
Which dot and cross diagram below shows the correct outer shell arrangement of electrons in a molecule of CO2?
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21 mark
A student has drawn a dot and cross diagram to represent a molecule of ethene, C2H4, as shown below.
What is wrong with the students drawing?
The number of electrons shared between the carbon atoms is incorrect.
The number of electrons shared between each carbon and hydrogen is incorrect.
There is nothing wrong with the drawing.
The total number of electrons shared is incorrect.
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31 mark
Dot and cross diagrams for four covalent molecules are shown below.
Which diagram is incorrect?
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41 mark
Which statement about methane is correct?
It has a high melting point due to strong covalent bonds between atoms
It has a low melting point due to weak covalent bonds between the molecules
It has a low boiling point due to weak intermolecular forces between molecules
It has a high boiling point because of strong intermolecular forces between molecules
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51 mark
A covalent molecule M contains a total of four shared electrons.
What is M?
Carbon dioxide
Oxygen
Nitrogen
Methane
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