Radioactivity Test

*32, A27,B23,C20.

1.       (a)     gamma;                                                                                                             1

(b)     (i)      beta;                                                                                                        1

(ii)     An explanation to include:

          1. alpha would not penetrate/alpha all absorbed/alpha
    stopped by paper/eq;
2. all gamma would penetrate (too much)/gamma not absorbed;

          [Accept alpha not strong enough and gamma is too strong/eq for 1 max] 2

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  2.     A

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  3.     (a)     (i)      5300 ± 100 (years) ;
[If the candidate has taken an average then allow the answer if correct] 1

(ii)     / 25%;                                                                                                  1

  (b)   (i)      very little/no measurable change in activity/not enough decay/graph
not accurate enough/no time to decay/relative statement 200 years :
5300 years;                                                                                             1

(ii)     An explanation to include:

          1. seeds/wooden utensils - yes;
2. as once-living/organic/carbon-14;
3. building stones no, as never-lived/do not contain carbon-14;
[Reject the third mark if either seeds or wooden utensils
included in this category]                                                               3

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  4.     B

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  5.     (a)     isotopes;                                                                                                           1

(b)     92 protons;
146 neutrons;                                                                                                   2

  (c)    (i)      fission;                                                                                                    1

(ii)     A description to include three from:

          1. neutron hits/strikes/absorbed by uranium (nucleus);
[Ignore cuts/slices through]
2. two smaller daughter nuclei/particles/elements/isotopes
    formed/uranium splits;
[Ignore fragments]
3. neutrons left over;
4. energy/kinetic energy/heat is released;
[Accept heating]                                                                            3

(d)     (i)      A description to include two valid points:

          eg      1. energy/heat being released/effect on container/eq;
          2. environmental issue/eq;                                                             2

(ii)     Any reasonable suggestion;
eg thick walls/concrete walls/lead (lined) walls/underground;
[Reject air tight]                                                                                       1

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  6.     (a)     (fast moving) electron/;              IGNORE : negative charges particle         1

  (b)   are stopped too easily/stopped by paper/low penetration/
/would not be detected outside plant/particles absorbed (by plant);                  1

  (c)   6mg //25%;                                                                                                   1

  (d)   phosphorus-30 decays too quickly(for this experiment)/
/too short a half life;
decays before it can be absorbed;                                                                    2

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  7.     (a)     (i)      (atomic) mass number/number of nucleons/
number of protons + neutrons;                                                                1
Ignore relative atomic mass unless qualified.

  (ii)   Any two from:
High (kinetic) energy/fast moving (particles);
negatively charged/electrons;
(emitted) from nucleus;                                                                           2

  (b)   (i)      by an increase in the radiation (detected)OWTTE;                                  1

  (ii)   it emits gamma (radiation); Reject beta.
(gamma) can penetrate the ground/others can not;                                  2

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  8.     (a)     An explanation to include:
waste radioactive / gives off radiation;
remains so for hundreds / thousands of years/ has long half-life;
radiation (can) cause mutations / cancers in living organisms /
upsets cell division;
leakage into ground water;
problems / dangers in transporting / locating disposal sites;                              3

  (b)   A description to include three of:
do not produce SO2 / nitrogen oxide;
causing acid rain;
do not produce CO2 ;
causing green house effect;
less air / atmospheric pollution;
saves on fossil fuels  (which can be used for other things);
more reliable than wind / solar / wave / HEP;                                                   3

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