1. (a) An explanation to include:
·
have the same number of protons;
·
but different numbers of neutrons; 2
(b)
Isotope
|
Stable
|
Excess
neutrons
|
Excess
protons
|
carbon-11
|
|
|
ü;
|
carbon-12
|
ü;
|
|
|
carbon-14
|
|
ü;
|
|
3
(c) (i)
Nucleus
|
Number
of neutrons
|
Number
of protons
|
|
carbon-15
|
9
|
6
|
;
|
nitrogen-15
|
8
|
7
|
;
|
2
(ii) A description to include:
·
a neutron changes to a proton;
and
emits an electron/b-; 2
[9]
2. (a) (i) particle
that cannot be broken down any further; 1
Allow:
no substructure
not made up of other particles
no substructure
not made up of other particles
(ii) accept
any correct particle; 1
Allow:
Electron /beta particle/e-positron
lepton
neutrino
Electron /beta particle/e-positron
lepton
neutrino
Ignore
antiquark
b) proton = (2 ×
2/3) – 1/3 = 1;
Subst
must be shown in some way +;
Allow
knowledge that p is positively charged
neutron
= 1u + 2d; 3
Allow
dud
allow in words
allow in words
(c) (i) down quark changes to up quark; 1
Allow:
now have udu/uud/duu
d becomes u
now have udu/uud/duu
d becomes u
(ii) (electron)
emitted from the nucleus (as a beta particle); 1
Allow
ejected
[7]
3. (a) above the ‘line’; 1
if
in doubt for points close to the ‘line’, look at the distance from the ‘line’
vertically
(b) (i) beta– particles; 1
(ii) increases; 1
(iii) stays
the same; 1
[4]
4. (a) (i) proton
number greater than 82; 1
(ii) above
the curve; 1
(b) (i) up and down; 1
(ii) 4
particle
|
total
number of
quarks |
number
of u
quarks |
number
of d
quarks |
neutron
|
3
|
1
|
XXX
|
proton
|
XXX
|
2
|
1
|
(iii) opposite;
twice charge on d; 2
twice charge on d; 2
(iv) proton; 1
(v) a
d becomes a u; 1
[11]