Assessed Homework

  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

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  2.     (a)     (i)      particle that cannot be broken down any further;                                    1

Allow:
no substructure
not made up of other particles

  (ii)   accept any correct particle;                                                                      1

Allow:
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

  (c)    (i)      down quark changes to up quark;                                                           1

Allow:
now have udu/uud/duu
d becomes u

  (ii)   (electron) emitted from the nucleus (as a beta particle);                          1

Allow ejected

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  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

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  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

  (iv)  proton;                                                                                                    1

  (v)   a d becomes a u;                                                                                     1

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  5.    

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