CAMBRIDGE INTERNATIONAL AS & A LEVEL CHEMISTRY: COURSEBOOK
Exam-style questions and sample answers have been written by the authors. In examinations, the way marks are awarded
may be different.
Coursebook answers
Chapter 1
Exam-style questions
protons = 5
[1]
ii
neutrons = 6
[1]
iii
electrons = 5
[1]
1
a
b
c
i
Isotopes are atoms of the same
element with different nucleon
numbers / mass numbers / different
numbers of neutrons.
i
mass =
1
1836
charge = −1
ii
[1]
mass = 1
[1]
[1]
mass = 1
[1]
[Total: 10]
a
i
ii
b
70
c
i
ii
d
91
40
Zr [1]
roton has positive charge, and
P
like charges repel / opposite
charges attract.
no deflection / go straight through;
[1]
atomic number = number of protons
(in the nucleus);
[1]
Mg = 12 protons, 12 electrons,
12 neutrons
[1]
[1]
d
number of positively charged protons
= number of negatively charged
electrons
[1]
e
it would not be oxygen / it would be
another element / oxygen can only
have 8 protons
f
4
a
[1]
The mass of an electron is negligible. [1]
Isotopes are atoms of the same
element with different nucleon
numbers / mass numbers / different
numbers of neutrons.
[1]
both have 92 protons;
[1]
both have 92 electrons
[1]
[1]
[1]
containing protons and neutrons;
[1]
[Total: 13]
[1]
positively charged nucleus;
or negligible]
Al = 13 protons, 13 electrons,
14 neutrons
[1]
[Total: 7]
a
c
[1]
I t is deflected / bends away from
the anode (or positive plate), or
towards the cathode (or negative
plate), or downwards.
1
2000
1
1836
nucleon number = number of protons +
number of neutrons
[1]
[1]
51
neutrons have no charge
3
b
[1]
charge = +1
2
[allow
[1]
charge = zero
iii
neutrons are neutral with relative
charge of zero and relative mass of 1; [1]
electrons are negative with relative
charge of −1 and relative mass of
[1]
protons are positively charged with relative
charge of +1 and relative mass of 1;
[1]
[1]
electrons outside the nucleus in energy
levels;
[1]
b
c
uranium-235 has 143 neutrons;
[1]
uranium-238 has 146 neutrons
[1]
d
90
[1]
[Total: 6]
1
Cambridge International AS & A Level Chemistry © Cambridge University Press 2020
CAMBRIDGE INTERNATIONAL AS & A LEVEL CHEMISTRY: COURSEBOOK
5
a
number of protons = 17 and 17
[1]
number of electrons = 17 and 17
[1]
number of neutrons in chlorine-35
= 18; in chlorine-37 = 20
[1]
b
the chlorine-35 isotope is more
abundant;
the weighted average is nearer 35
than 37
c
[1]
[1]
i
it has more protons than electrons [1]
ii
it has 17 protons and 18 electrons /
it has 1 more electron than protons [2]
[it has more electrons than
protons for 1 mark]
[Total: 8]
2
Cambridge International AS & A Level Chemistry © Cambridge University Press 2020