Question
Answer                               Notes            Marks
 number
1 (a) (i)      C (decreases by 2)                                                             1
        (ii)   D (decreases by 4)                                                             1
  (b)          D (has less penetrating power)                                                 1
  (c)          Any four of:                                                                   4
               MP1 Use of ratemeter / scaler / counter;          Allow description e.g.
                                                                 “count the clicks”
                                                                 Allow Geiger counter
                                                                 Ignore GM detector or
                                                                 tube
                                                                 Ignore descriptions of
                                                                 GM tube
               MP2 Idea of measuring background radiation
               e.g. background count / correction
               /subtraction;
               MP3 A safety precaution (based on distance or     Allow
               absorption) e.g. use of tongs / shielding;        “stand back”,
                                                                 “wear gloves /
                                                                 protective clothing”
                                                                 “do not point source
                                                                 at people”
               MP4 A controlled variable (time / distance /      Ignore “counts per
               positioning) e.g. “source near/by/to detector”,   minute”
               “for a minute”;
               MP5 A practical consideration e.g. repeat /       Ignore:
               average / reset (scaler);                         mention of anomalies
               MP6 Mention of becquerel / Bq                     Accept phonetic
                                                                 spellings
                                     Total for question 1 = 7 marks
Question
                                Answer           Notes   Marks
number
           A   activi y
                                                           1
2 (a)
           A   alpha particle
                                                           1
  (b)
           B   beta particle
                                                           1
  (c)
           A   alpha particle
                                                           1
  (d)
                                         Total
                                          o               4
Question
                              Answer                                   Accept           Reject       Marks
 number
3        An explanation including any five of these ideas (in                                            5
         any order):                                            Accept reverse
                                                                arguments, e.g. beta
           MP1 alpha particles have less penetrating power      particles have more
           /less range ;                                        penetrating power etc
                                                                Ignore comparisons of
           MP2 alphas have more charge;                         energy/ velocity/
           MP3 alphas cause more ionization;                    momentum
           MP4 alphas are bigger / have more mass;
           MP5 (slowing) force on alpha particles is larger;
           MP6 (kinetic) energy of alpha lost quickly causing
           ionization;
           MP7 (larger) alpha particles are more likely to
           collide with atoms;
                                                                                                 Total 5 marks
 Question
                                 Answer                               Notes             Marks
  number
4 (a)          idea that background activity should be                                     1
               subtracted (from each reading);
  (b)          time taken;                                    allow “how long it           2
                                                              takes”
               and either
               for amount of (radioactive) nuclei / atoms     allow
               / isotope to halve;                             decay by half
                                                               decay to half
               OR
               for (radio)activity to halve                   ignore particles /
                                                              molecules,
                                                              “breakdown”,
                                                              “reactivity”
                                                              reject if implies a
                                                              single nucleus/atom
  (c)   (i)    evidence of use of graph;                      e.g. lines to two            2
                                                              correct points on
                                                              graph or appropriate
                                                              subtraction shown in
                                                              working
               56 ± 3 (s);
        (ii)   any 1 from:                                    allow                        1
               MP1. idea of {more accurate / smoother}        more points to plot on
                    curve;                                    graph
               MP2. idea that activity changes quickly;       decays quickly
               MP3. idea that decay takes very little time;   (sample has) short
                                                              half life
                                                                                   Total 6 marks
Question
                                 Answer                               Notes             Marks
 number
5 (a) (i)      90                                                                          1
        (ii)   time;                                                                       2
                                                              Allow for amount -
               either
               for amount of (radioactive) isotope to         (number of un-
               halve;                                         decayed)
                                                              nuclei/atoms/molecules
                                                              (un-decayed) mass of
                                                              isotope
               or
               for (radio)activity to halve;
        (iii) Any two of –                                                                 2
               MP1 Idea that (beta) radiation causes a        e.g. causes cancer,
               stated hazard;                                 kills cells, mutates
                                                              DNA, ionises tissue
               MP2 Idea that strontium-90 has a long          Accept lasts a long
               half-life;                                     time
               MP3 Idea that all beta emission will be        Accept answers in
               absorbed by the body;                          terms of range
  (b)   (i)    90 and 0;                                      Must have both               2
               -1;                                            Minus is essential
                                                         β-
        (ii)   Any two ideas from –                                                        2
               MP1 They are isotopes of different
               elements;
               MP2 Strontium-90 (nucleus/atom) has the        Allow use of proton
               same number of protons as other                number data (38)
               strontium (nuclei/atoms);
               MP3 Yttrium-90 (nucleus/atom) has the           Allow use of proton
               same number of protons as other yttrium        number data (39)
               (nuclei/atoms);
                                                                        Total 9 marks
Question
                                Answer                                              Notes                      Marks
 number
6 (a) (i)   B (53)                                                                                                  1
        (ii) D (131)                                                                                                1
  (b)       Any two of -                                                                                            2
            MP1 Beta is (moderately) ionising;                 Ignore I-131 is radioactive, it emits beta
            MP2 Beta has a short range;
            MP3 idea that I-131 has a short half-life;
            MP4 idea that iodine is absorbed (easily) by the
            thyroid;
            MP5 (hence) reduces damage to healthy cells;
            MP6 (hence) does not penetrate out of the body;
            MP7 (therefore) kills (only) tumour cells;
                                                                                                            Total 4 marks
 Question
                                 Answer                     Accept         Reject   Marks
 number
7 (a)                                                                                 2
            Type of           C
                              Charge
                                harge S
            radiation                                ++                -
                                          Unstable
             Alpha particle     (+)2
                                           nucleus   Unstable nuclei
                                          Unstable
             Beta particle      -
                                           nucleus
                                          Unstable
              Gamma ray          0
                                          nucleus
            (As shown)
            2;
            Unstable nucleus;
 Question
                                     Answe
                                         er                                Accept             Reject            Marks
 number
7 (b)          Any three of:                                       Ign
                                                                     nore references to                           3
                                                                   dan
                                                                     nger or harm
               MP1 - Idea that alpha particles would not
               penetrate (enough);                                 All ideas may be
               e.g. alpha particles absorbed / stopped by          exppressed in terms of
               {aluminium / foil / a few cm
                                          m air / paper / card}    pennetration or
                                                                   abssorption.
               MP2 - Idea that gamma rayys would be too
               penetrative;                                        No need to see the
               e.g. gamma rays {are not absorbed / are
                                                     e             word “aluminiumm,”
               unaffected}                                         proovided the meaning
                                                                   is clear.
               MP3 - Idea that some beta particles will pass
               through the foil;                                   Acc
                                                                     cept paper or card
               e.g. not all off the beta partticles are absorbed   willl stop alpha for MP1
               MP4 - Idea of a correlation between thickness       Acccept comparisons of
               and absorptioon;                                    aluminium thickness
               e.g. thinner aluminium absorbs fewer beta           for MP4
               particles
  (c)   (i)                                                                                                       1
               both 90 and 39 for mark
        (ii)   B (the number of protons increases);                                                               1
                                                                                                       To
                                                                                                        ottal    7
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