Radiactivity Homework

1.       (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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  2.     (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

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3.       (a)     (i)      An explanation to include:

1.  radiation absorbed by the steel / concrete /
stops radiation escaping;                                                                2

2.  safety / health;

  (ii)   Any two from:

1.  cancer;

2.  sickness;

3.  nausea;

4.  loss of hair;

5.  sterility;

6.  cell /tissue damage;                                                                        2

  (iii)  radioactive for a long period after removal /                                           1
radioactive /dangerous for along time;

  (b)   (i)      chain reaction/ (nuclear) fission;                                                             1

(ii)     kinetic / movement energy;                                                                     1

  (iii)  An explanation to include three from:

1.  kinetic energy transferred;

2.  to heat energy;

3.  used to produce steam;

4.  to drive turbines / generator;

5.  generator produces electricity;                                                       3

          plus 1 communication mark for use of a suitable structure and style      1
of writing;
[Communication mark – at least two linked ideas]

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  4.     C

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  5.     Suitable diagram and/or description to illustrate experiment up to 2 marks (2)

          Experiment must be carried out in a vacuum (1)
Most particles have little if any deflection (1)

          Very small number of particles have large deflection/back scattering (1)
This shows the nucleus is very small (and positive) (1); and very dense (1)

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