Syllabus Edition
First teaching 2023
First exams 2025
In acidic conditions, ammonia, NH3, reacts with a proton, H+, to form ammonium NH4+.
Using the following key:
• N electron
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H electron
Which of the following Dot & Cross diagrams correctly illustrate electron movement in this reaction?
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In which species does the underlined atom have an incomplete outer shell?
H3O+
CH3-
BF3
MgO
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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?
0
2
5
6
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Three lone pairs of electrons can be found around the central atom of which of the following ions?
PF6−
ClF2−
BF2−
SF5−
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How many lone pairs of electrons are there in a chlorine trifluoride, ClF3, molecule?
1
2
3
0
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Which of the following molecules obeys the octet rule?
BF3
HCN
BeCl2
CS2
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Calcium Oxide, CaO2, can be used in toothpaste as a teeth whitener. It is formed when calcium metal burns in oxygen. Which dot-and-cross diagram correctly illustrates the electron structure of the peroxide ion in CaO2.
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Which of the following statements about 2-chloropropene, CH2C(Cl)CH3 is not correct
There are 3 lone pairs in the molecule
There are 24 valence electrons in the molecule
The molecule does obey the octet rule
The molecule does not obey the octet rule
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The number of electrons in the valence shell of elements X and Y are 5 and 7 respectively. What is the formula and type of compound formed from these elements?
Covalent, XY3
Ionic, XY3
Covalent, X3Y
Ionic, X3Y
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