physics for examination from 2023
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Cambridge IGCSE™
PHYSICS 0625/04Paper 4 Theory (Extended) For examination from 2023MARK SCHEME
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Gen
eric
Mar
king
Prin
cipl
es
Thes
e ge
nera
l mar
king
prin
cipl
es m
ust b
e ap
plie
d by
all
exam
iner
s w
hen
mar
king
can
dida
te a
nsw
ers.
The
y sh
ould
be
appl
ied
alon
gsid
e th
e sp
ecifi
c co
nten
t of t
he m
ark
sche
me
or g
ener
ic le
vel d
escr
ipto
rs fo
r a q
uest
ion.
Eac
h qu
estio
n pa
per a
nd m
ark
sche
me
will
als
o co
mpl
y w
ith th
ese
mar
king
pr
inci
ples
.
GE
NE
RIC
MA
RK
ING
PR
INC
IPLE
1:
Mar
ks m
ust b
e aw
arde
d in
line
with
:
•th
e sp
ecifi
c co
nten
t of t
he m
ark
sche
me
or th
e ge
neric
leve
l des
crip
tors
for t
he q
uest
ion
•th
e sp
ecifi
c sk
ills
defin
ed in
the
mar
k sc
hem
e or
in th
e ge
neric
leve
l des
crip
tors
for t
he q
uest
ion
•th
e st
anda
rd o
f res
pons
e re
quire
d by
a c
andi
date
as
exem
plifi
ed b
y th
e st
anda
rdis
atio
n sc
ripts
.
GE
NE
RIC
MA
RK
ING
PR
INC
IPLE
2:
Mar
ks a
war
ded
are
alw
ays
who
le m
arks
(not
hal
f mar
ks, o
r oth
er fr
actio
ns).
GE
NE
RIC
MA
RK
ING
PR
INC
IPLE
3:
Mar
ks m
ust b
e aw
arde
d po
sitiv
ely:
•m
arks
are
aw
arde
d fo
r cor
rect
/val
id a
nsw
ers,
as
defin
ed in
the
mar
k sc
hem
e. H
owev
er, c
redi
t is
give
n fo
r val
id a
nsw
ers
whi
ch g
o be
yond
the
scop
e of
the
sylla
bus
and
mar
k sc
hem
e, re
ferr
ing
to y
our T
eam
Lea
der a
s ap
prop
riate
•m
arks
are
aw
arde
d w
hen
cand
idat
es c
lear
ly d
emon
stra
te w
hat t
hey
know
and
can
do
•m
arks
are
not
ded
ucte
d fo
r err
ors
•m
arks
are
not
ded
ucte
d fo
r om
issi
ons
•an
swer
s sh
ould
onl
y be
judg
ed o
n th
e qu
ality
of s
pelli
ng, p
unct
uatio
n an
d gr
amm
ar w
hen
thes
e fe
atur
es a
re s
peci
fical
ly a
sses
sed
by th
e qu
estio
n as
indi
cate
d by
the
mar
k sc
hem
e. T
he m
eani
ng, h
owev
er, s
houl
d be
una
mbi
guou
s.
GE
NE
RIC
MA
RK
ING
PR
INC
IPLE
4:
Rul
es m
ust b
e ap
plie
d co
nsis
tent
ly, e
.g. i
n si
tuat
ions
whe
re c
andi
date
s ha
ve n
ot fo
llow
ed in
stru
ctio
ns o
r in
the
appl
icat
ion
of g
ener
ic le
vel
desc
ripto
rs.
GE
NE
RIC
MA
RK
ING
PR
INC
IPLE
5:
Mar
ks s
houl
d be
aw
arde
d us
ing
the
full
rang
e of
mar
ks d
efin
ed in
the
mar
k sc
hem
e fo
r the
que
stio
n (h
owev
er; t
he u
se o
f the
full
mar
k ra
nge
may
be
lim
ited
acco
rdin
g to
the
qual
ity o
f the
can
dida
te re
spon
ses
seen
).
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GE
NE
RIC
MA
RK
ING
PR
INC
IPLE
6:
Mar
ks a
war
ded
are
base
d so
lely
on
the
requ
irem
ents
as
defin
ed in
the
mar
k sc
hem
e. M
arks
sho
uld
not b
e aw
arde
d w
ith g
rade
thre
shol
ds o
r gra
de
desc
ripto
rs in
min
d.
Scie
nce-
Spec
ific
Mar
king
Prin
cipl
es
1 E
xam
iner
s sh
ould
con
side
r the
con
text
and
sci
entif
ic u
se o
f any
key
wor
ds w
hen
awar
ding
mar
ks. A
lthou
gh k
eyw
ords
may
be
pres
ent,
mar
ks
shou
ld n
ot b
e aw
arde
d if
the
keyw
ords
are
use
d in
corr
ectly
.
2 Th
e ex
amin
er s
houl
d no
t cho
ose
betw
een
cont
radi
ctor
y st
atem
ents
giv
en in
the
sam
e qu
estio
n pa
rt, a
nd c
redi
t sho
uld
not b
e aw
arde
d fo
r any
co
rrec
t sta
tem
ent t
hat i
s co
ntra
dict
ed w
ithin
the
sam
e qu
estio
n pa
rt. W
rong
sci
ence
that
is ir
rele
vant
to th
e qu
estio
n sh
ould
be
igno
red.
3 A
lthou
gh s
pelli
ngs
do n
ot h
ave
to b
e co
rrec
t, sp
ellin
gs o
f syl
labu
s te
rms
mus
t allo
w fo
r cle
ar a
nd u
nam
bigu
ous
sepa
ratio
n fro
m o
ther
syl
labu
s te
rms
with
whi
ch th
ey m
ay b
e co
nfus
ed (e
.g. e
than
e / e
then
e, g
luca
gon
/ gly
coge
n, re
fract
ion
/ ref
lect
ion)
.
4 Th
e er
ror c
arrie
d fo
rwar
d (e
cf) p
rinci
ple
shou
ld b
e ap
plie
d, w
here
app
ropr
iate
. If a
n in
corr
ect a
nsw
er is
sub
sequ
ently
use
d in
a s
cien
tific
ally
co
rrec
t way
, the
can
dida
te s
houl
d be
aw
arde
d th
ese
subs
eque
nt m
arki
ng p
oint
s. F
urth
er g
uida
nce
will
be
incl
uded
in th
e m
ark
sche
me
whe
re
nece
ssar
y an
d an
y ex
cept
ions
to th
is g
ener
al p
rinci
ple
will
be
note
d.
5 ‘L
ist r
ule’
gui
danc
e
Fo
r que
stio
ns th
at re
quire
n re
spon
ses
(e.g
. Sta
te tw
o re
ason
s …
):
•Th
e re
spon
se s
houl
d be
read
as
cont
inuo
us p
rose
, eve
n w
hen
num
bere
d an
swer
spa
ces
are
prov
ided
. •
Any
resp
onse
mar
ked
igno
re in
the
mar
k sc
hem
e sh
ould
not
cou
nt to
war
ds n
. •
Inco
rrec
t res
pons
es s
houl
d no
t be
awar
ded
cred
it bu
t will
stil
l cou
nt to
war
ds n
. •
Rea
d th
e en
tire
resp
onse
to c
heck
for a
ny re
spon
ses
that
con
tradi
ct th
ose
that
wou
ld o
ther
wis
e be
cre
dite
d. C
redi
t sho
uld
not b
e aw
arde
d fo
r any
resp
onse
s th
at a
re c
ontra
dict
ed w
ithin
the
rest
of t
he re
spon
se. W
here
two
resp
onse
s co
ntra
dict
one
ano
ther
, thi
s sh
ould
be
trea
ted
as a
sin
gle
inco
rrec
t res
pons
e. •
Non
-con
tradi
ctor
y re
spon
ses
afte
r the
firs
t n re
spon
ses
may
be
igno
red
even
if th
ey in
clud
e in
corr
ect s
cien
ce.
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6 C
alcu
latio
n sp
ecifi
c gu
idan
ce
C
orre
ct a
nsw
ers
to c
alcu
latio
ns s
houl
d be
giv
en fu
ll cr
edit
even
if th
ere
is n
o w
orki
ng o
r inc
orre
ct w
orki
ng, u
nles
s th
e qu
estio
n st
ates
‘sho
w
your
wor
king
’.
Fo
r que
stio
ns in
whi
ch th
e nu
mbe
r of s
igni
fican
t fig
ures
requ
ired
is n
ot s
tate
d, c
redi
t sho
uld
be a
war
ded
for c
orre
ct a
nsw
ers
whe
n ro
unde
d by
th
e ex
amin
er to
the
num
ber o
f sig
nific
ant f
igur
es g
iven
in th
e m
ark
sche
me.
Thi
s m
ay n
ot a
pply
to m
easu
red
valu
es.
Fo
r ans
wer
s gi
ven
in s
tand
ard
form
(e.g
. a ×
10n ) i
n w
hich
the
conv
entio
n of
rest
rictin
g th
e va
lue
of th
e co
effic
ient
(a) t
o a
valu
e be
twee
n 1
and
10 is
not
follo
wed
, cre
dit m
ay s
till b
e aw
arde
d if
the
answ
er c
an b
e co
nver
ted
to th
e an
swer
giv
en in
the
mar
k sc
hem
e.
U
nles
s a
sepa
rate
mar
k is
giv
en fo
r a u
nit,
a m
issi
ng o
r inc
orre
ct u
nit w
ill n
orm
ally
mea
n th
at th
e fin
al c
alcu
latio
n m
ark
is n
ot a
war
ded.
E
xcep
tions
to th
is g
ener
al p
rinci
ple
will
be
note
d in
the
mar
k sc
hem
e.
7 G
uida
nce
for c
hem
ical
equ
atio
ns
M
ultip
les
/ fra
ctio
ns o
f coe
ffici
ents
use
d in
che
mic
al e
quat
ions
are
acc
epta
ble
unle
ss s
tate
d ot
herw
ise
in th
e m
ark
sche
me.
S
tate
sym
bols
giv
en in
an
equa
tion
shou
ld b
e ig
nore
d un
less
ask
ed fo
r in
the
ques
tion
or s
tate
d ot
herw
ise
in th
e m
ark
sche
me.
Mar
k ca
tego
ries
B m
arks
Thes
e ar
e in
depe
nden
t mar
ks, w
hich
do
not d
epen
d on
oth
er m
arks
. For
a B
mar
k to
be
awar
ded,
the
poin
t to
whi
ch it
refe
rs m
ust b
e se
en s
peci
fical
ly in
the
cand
idat
e’s
answ
er.
M m
arks
Thes
e ar
e m
etho
d m
arks
upo
n w
hich
A m
arks
late
r dep
end.
For
an
M m
ark
to b
e aw
arde
d, th
e po
int t
o w
hich
it re
fers
mus
t be
seen
sp
ecifi
cally
in th
e ca
ndid
ate’
s an
swer
. If a
can
dida
te is
not
aw
arde
d an
M m
ark,
the
late
r A m
ark
cann
ot b
e aw
arde
d ei
ther
.
C m
arks
Thes
e ar
e co
mpe
nsat
ory
mar
ks w
hich
can
be
awar
ded
even
if th
e po
ints
to w
hich
they
refe
r are
not
writ
ten
dow
n by
the
cand
idat
e,
prov
idin
g su
bseq
uent
wor
king
giv
es e
vide
nce
that
they
mus
t hav
e kn
own
them
. For
exa
mpl
e, if
an
equa
tion
carr
ies
a C
mar
k an
d th
e ca
ndid
ate
does
not
writ
e do
wn
the
actu
al e
quat
ion
but d
oes
corr
ect w
orki
ng w
hich
sho
ws
the
cand
idat
e kn
ew th
e eq
uatio
n, th
en th
e C
m
ark
is a
war
ded.
If a
corr
ect a
nsw
er is
giv
en to
a n
umer
ical
que
stio
n, a
ll of
the
prec
edin
g C
mar
ks a
re a
war
ded
auto
mat
ical
ly. It
is o
nly
nece
ssar
y to
co
nsid
er e
ach
of th
e C
mar
ks in
turn
whe
n th
e nu
mer
ical
ans
wer
is n
ot c
orre
ct.
A m
arks
Thes
e ar
e an
swer
mar
ks. T
hey
may
dep
end
on a
n M
mar
k or
allo
w a
C m
ark
to b
e aw
arde
d by
impl
icat
ion.
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Abb
revi
atio
ns a
nd g
uida
nce
/A
ltern
ativ
e an
swer
s fo
r the
sam
e m
arki
ng p
oint
.
unde
rline
Act
ual w
ord
unde
rline
d m
ust b
e us
ed b
y ca
ndid
ate
(gra
mm
atic
al v
aria
nts
acce
pted
).
(bra
cket
s)Th
e w
ord
or p
hras
e in
bra
cket
s is
not
requ
ired
but s
ets
the
cont
ext.
AND / a
ndS
tate
men
ts o
n bo
th s
ides
of t
he A
ND
are
nee
ded
for t
hat m
ark.
OR / o
rIn
dica
tes
alte
rnat
ive
answ
ers,
any
one
of w
hich
is s
atis
fact
ory
for s
corin
g th
e m
arks
.
NOT / not
Indi
cate
s th
at a
n in
corr
ect a
nsw
er is
not
to b
e di
sreg
arde
d bu
t can
cels
ano
ther
oth
erw
ise
corr
ect a
ltern
ativ
e of
fere
d by
the
cand
idat
e fo
r thi
s m
ark.
Accept / Acc
A le
ss th
an id
eal a
nsw
er w
hich
sho
uld
be m
arke
d co
rrec
t.
Igno
re / Ig
Indi
cate
s th
at s
omet
hing
whi
ch is
not
cor
rect
or i
rrel
evan
t is
to b
e di
sreg
arde
d.
e.c.
f.‘e
rror
car
ried
forw
ard’
o.w
.t.t.e
.‘o
r wor
ds to
that
effe
ct’
s.f.
‘sig
nific
ant f
igur
es’ –
ans
wer
s ar
e no
rmal
ly a
ccep
tabl
e to
any
num
ber o
f sig
nific
ant f
igur
es ⩾
2. A
ny e
xcep
tions
to th
is g
ener
al
rule
will
be
spec
ified
in th
e m
ark
sche
me.
Arit
hmet
ic e
rror
sIf
the
only
err
or in
arr
ivin
g at
a fi
nal a
nsw
er is
cle
arly
an
arith
met
ic o
ne, a
ll bu
t the
fina
l A m
ark
can
be a
war
ded.
Reg
ard
a po
wer
of t
en e
rror
as
an a
rithm
etic
err
or.
Tran
scrip
tion
erro
rsIf
the
only
err
or in
arr
ivin
g at
a fi
nal a
nsw
er is
bec
ause
giv
en o
r pre
viou
sly
calc
ulat
ed d
ata
has
clea
rly b
een
mis
read
but
use
d co
rrec
tly, a
ll bu
t the
fina
l A m
ark
can
be a
war
ded.
Frac
tions
Onl
y ac
cept
thes
e w
here
spe
cifie
d in
the
mar
k sc
hem
e.
Cro
ssed
-out
wor
kW
ork
whi
ch h
as b
een
cros
sed
out a
nd n
ot re
plac
ed b
ut c
an e
asily
be
read
, sho
uld
be m
arke
d as
if it
had
not
bee
n cr
osse
d ou
t.
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Que
stio
nA
nsw
erM
arks
1(a)
men
tion
of g
radi
ent o
f gra
ph a
t t =
30
s O
R ta
ngen
t dra
wn
at t
= 30
s a
nd tr
iang
le d
raw
n O
R v
alue
s of
t an
d v
take
n fro
m
grap
hC
1
α =
tvD D
OR
cal
cula
tion
show
n
C1
acce
lera
tion
in ra
nge
0.30
to 0
.45
m /
s2A
1
1(b)
acce
lera
tion
less
/ at
a s
low
er ra
teB
1
less
driv
ing
forc
e O
R g
reat
er re
sist
ive
forc
e / f
rictio
n / a
ir re
sist
ance
/ dr
ag A
ND
resu
ltant
forc
e le
ssB
1
1(c)
area
und
er g
raph
/ ar
ea u
nder
line
C1
dist
ance
= (2
0 ×
40) +
(21
× 4
0 ×
10) O
R 21
× (3
0 +
20) ×
40
C1
1000
mA
1
Que
stio
nA
nsw
erM
arks
2(a)
forc
eB
1
impu
lse
B1
2(b)
(i)(p
=) m
v O
R 0
.046
× 6
5C
1
3.0
kg m
/ s
OR
3.0
N s
A1
2(b)
(ii)
(F =
) (
)t
mvu
− o
r ..
000050
30
OR
a = (
)t
vu
− a
nd F
= m
a or
.. 000050
0046
65#
or
0.04
6 ×
130
000
C1
6000
NO
R60
00 N
A1
2(b)
(iii)
elas
tic (e
nerg
y) O
R s
train
(ene
rgy)
B1
0625
/04
Cam
brid
ge IG
CS
E –
Mar
k S
chem
e Fo
r exa
min
atio
n
SPEC
IMEN
fro
m 2
023
Pag
e 7
of 1
2©
UC
LES
202
0
Que
stio
nA
nsw
erM
arks
3(a)
(i)nu
clea
r fus
ion
B1
3(a)
(ii)
nucl
ei c
ombi
ne /
join
toge
ther
B1
smal
l nuc
lei t
o la
rger
nuc
lei O
R h
ydro
gen
to h
eliu
m (i
n so
me
way
) OR
loss
of m
ass
B1
3(b)
any
suita
ble
reso
urce
, e.g
. fos
sil f
uels
; hyd
roel
ectri
c; w
ave;
win
d N
OT
geot
herm
al, n
ucle
arM
1
rene
wab
le O
R n
ot (a
ccor
ding
ans
wer
) AN
D m
atch
ing
expl
anat
ion
A1
3(c)
any
two
adva
ntag
es fr
om: n
o po
llutin
g ga
ses
/ qui
et /
low
mai
nten
ance
/ ca
n be
pla
ced
on ro
ofs
/ cle
an /
chea
p to
run
B2
any
two
disa
dvan
tage
s fro
m: i
nter
mitt
ent s
uppl
y / u
nattr
activ
e / t
akes
up
spac
e / u
ses
land
/ d.c
. out
put
B2
Que
stio
nA
nsw
erM
arks
4(a)
atom
s co
llide
with
wal
l (an
d re
boun
d) O
R a
tom
s re
boun
d fro
m w
all
B1
(ato
ms)
und
ergo
cha
nge
of m
omen
tum
C1
forc
e on
wal
l = (t
otal
) rat
e of
cha
nge
of m
omen
tum
(of a
tom
s)O
R =
cha
nge
of m
omen
tum
(of a
tom
s) p
er s
econ
dO
R =
cha
nge
of m
omen
tum
(of a
tom
s) /
time
A1
4(b)
(i)fe
wer
ato
ms
per u
nit v
olum
e O
R d
ensi
ty o
f gas
less
B1
rate
of c
ollis
ion
(with
wal
ls o
f bal
loon
) dec
reas
es O
R fe
wer
col
lisio
ns p
er u
nit a
rea
B1
4(b)
(ii)
PV
= c
onst
ant O
R P
1V1
= P
2V2
OR
(P2
=) VPV 2
11 O
R .
.12
10
1096
5#
#C
1
8.0 ×
104 P
aA
1
Que
stio
nA
nsw
erM
arks
5(a)
arra
ngem
ent:
Ice:
in la
ttice
/ re
gula
r / a
rran
ged
/ ord
erly
/ fix
ed in
pla
ceW
ater
: ran
dom
/ irr
egul
ar /
not a
rran
ged
/ not
ord
erly
mot
ion:
Ice:
vib
rate
Wat
er: m
ove
(aro
und)
or s
lide
over
eac
h ot
her
B2
0625
/04
Cam
brid
ge IG
CS
E –
Mar
k S
chem
e Fo
r exa
min
atio
n
SPEC
IMEN
fro
m 2
020
Pag
e 8
of 1
2©
UC
LES
202
0
Que
stio
nA
nsw
erM
arks
5(b)
(i)d
= Vm
in a
ny fo
rm O
R (m
=) V
d O
R 1
800 ×
0.02
5 ×
920
C1
41 0
00 k
gA
1
5(b)
(ii)
(∆E
=) c
m∆θ
OR
2.1
× 1
03 × 4
1 00
0 ×
3.5
C1
3.0 ×
108 (J
) A
1
Que
stio
nA
nsw
erM
arks
6(a)
(i)an
y tw
o ra
ys th
at s
tart
at th
e to
p of
the
imag
e fro
m:
•se
ems
to c
ome
from
F1
to le
ns a
nd e
mer
ges
para
xial
ly •
pass
es th
roug
h ce
ntre
of l
ens
unde
viat
ed •
para
xial
to th
e le
ns a
nd p
asse
s th
roug
h F 2
M2
two
corr
ect r
ays
trace
d ba
ck a
nd im
age
indi
cate
dA
1
6(a)
(ii)
any
two
of: e
nlar
ged
/ inv
erte
d / r
eal u
nder
lined
B1
enla
rged
AN
D in
verte
d A
ND
real
und
erlin
edB
1
6(b)
refra
cted
ray
in p
rism
bel
ow y
ello
w ra
y A
ND
abo
ve n
orm
alB
1
emer
gent
ray
dive
rgin
g aw
ay fr
om th
e ye
llow
ray
AN
D o
utsi
de o
f pris
mB
1
Que
stio
nA
nsw
erM
arks
7(a)
330–
350
m /
sB
1
7(b)
v =
fλ O
R (f
=)
v m O
R .()a
0022
C1
Cor
rect
ans
wer
: e.g
. 330
m /
s gi
ves
15 0
00 H
zA
1
7(c)
use
of tr
ansd
ucer
to s
end
and
rece
ive
puls
es o
f ultr
asou
ndB
1
(dis
play
use
d to
det
erm
ine)
tim
e fo
r ech
o of
pul
se to
retu
rn fr
om fr
ont A
ND
bac
k of
bub
ble
B1
use
of s
peed
of s
ound
in th
e m
etal
B1
use
of d
ista
nce
= sp
eed ×
time
to c
alcu
late
pos
ition
and
siz
eB
1
0625
/04
Cam
brid
ge IG
CS
E –
Mar
k S
chem
e Fo
r exa
min
atio
n
SPEC
IMEN
fro
m 2
023
Pag
e 9
of 1
2©
UC
LES
202
0
Que
stio
nA
nsw
erM
arks
8(a)
RS =
RA +
RB in
any
form
OR
(RS =
) RA +
RB O
R (R
S =
) 4 +
8C
1
(RS =
) 12
(Ω)
C1
(RP =
) 1
11
RR
SC
+b
l in a
ny fo
rm
OR
(RP =
) (
)R
RR
R
SC
SC
+
OR
(RP =
)
12161
1 +d
n OR
(RP =
) (
)186
12#
C1
(RP =
) 4.0
ΩA
1
8(b)
V8
= su
pply
V ×
128 dn O
R =
24 × 128 dn
C1
(V8
=) 1
6 V
A1
OR
alte
rnat
ive
rout
e
I 8 =
V12
supply
OR
= 1224
OR
= 2
(A)
C1
(V8
= 2 ×
8 =)
16
VA
1
Que
stio
nA
nsw
erM
arks
9(a)
ball
gets
–ve
cha
rge
(from
–ve
pla
te)
B1
–ve(
ly c
harg
ed b
all)
attra
cted
to +
ve /
repe
lled
from
–ve
B1
9(b)
parti
cles
: ele
ctro
nsB
1
dire
ctio
n: fr
om le
ft to
righ
t (th
roug
h am
met
er)
B1
0625
/04
Cam
brid
ge IG
CS
E –
Mar
k S
chem
e Fo
r exa
min
atio
n
SPEC
IMEN
fro
m 2
020
Pag
e 10
of 1
2©
UC
LES
202
0
Que
stio
nA
nsw
erM
arks
9(c)
Q =
It i
n an
y fo
rm O
R tQ
wor
ds, n
umbe
rs, s
ymbo
lsC
1
corr
ect u
se o
f f =
4 H
z O
R T
= 0
.25
s i.e
. 8.5
× 1
0–10 ×
4 O
R
..025
85
1010
#-
C1
(I =
) 3.4
× 1
0–9 A
A1
Que
stio
nA
nsw
erM
arks
10(a
)(i)
Np
93237
B1
24 aB
1
10(a
)(ii)
gam
ma
and
beta
will
not
pro
duce
eno
ugh
ions
/ io
n pa
irs p
er c
mB
1
10(b
)(N
o of
Am
ato
ms
rem
aini
ng =
8 ×
1014
– 6
× 1
014) =
2 ×
1014
C1
4 ×
1014
(Am
ato
ms
rem
ain
afte
r 470
yrs
or 1
hal
f-life
)C
1
(2 ×
1014
Am
ato
ms
rem
ain
afte
r) 9
40 y
rs o
r 2 h
alf-l
ives
A1
Que
stio
nA
nsw
erM
arks
11(a
)hy
drog
en g
as in
ste
llar c
loud
/ ne
bula
pul
led
toge
ther
by
grav
ityB
1
tem
pera
ture
of h
ydro
gen
incr
ease
s A
ND
a p
roto
star
is fo
rmed
B1
nucl
ear f
usio
n be
gins
and
out
war
d fo
rce
from
this
reac
tion
bala
nces
inw
ard
forc
e of
gra
vity
B1
11(b
)an
y th
ree
from
:m
icro
wav
e ra
diat
ion
is o
bser
ved
at a
ll po
ints
in s
pace
aro
und
the
Ear
th o
.w.t.
t.e.
radi
atio
n w
as p
rodu
ced
whe
n th
e U
nive
rse
was
form
edth
is ra
diat
ion
has
expa
nded
into
the
mic
row
ave
regi
on o
f the
ele
ctro
mag
netic
spe
ctru
mth
is is
evi
denc
e th
at th
e U
nive
rse
expa
nded
B3
0625
/04
Cam
brid
ge IG
CS
E –
Mar
k S
chem
e Fo
r exa
min
atio
n
SPEC
IMEN
fro
m 2
023
Pag
e 11
of 1
2©
UC
LES
202
0
Que
stio
nA
nsw
erM
arks
12(a
)NN
VV
ps
ps=
in a
ny fo
rm O
R (N
s =)
VN
V
p
ps
#
OR
240
8000
6#
C1
200
A1
12(b
)I pV
p =
I sVs i
n an
y fo
rm O
R (I
p =)
IV
V p
ss
# O
R . 240
20
6#
C1
0.05
0 A
A1
0625
/04
Cam
brid
ge IG
CS
E –
Mar
k S
chem
e Fo
r exa
min
atio
n
SPEC
IMEN
fro
m 2
020
Pag
e 12
of 1
2©
UC
LES
202
0
BLA
NK
PA
GE