Questions on Nuclear physics
1. (i) thermionic emission; 1
(ii) A description to include three from:
1. heat in filament (releases electrons);
2. reference to 50 kV supply;
3. KE (due to electric field);
4. wave energy/energy of X-rays/heat; 3
(iii) (50 kV) power supply; 1
[Reject heater filament]
(iv) e × V;
= 1.6 × 10–19 × 50 × 1000 = 8 × 10–15 (J);
[Bald correct answer scores 2 marks]
[Allow 50 KeV for 2 marks] 2
[7]
2. (a) 0 and – 1 for ;
234 and 91 for Pa; 2
(b) An explanation to include:
1. gamma ray a wave;
2. no mass/protons; 2
[4]
3. (a) atomic mass of alpha is 4/alpha is 2n + 2p; 1
(b) (i) look at ranges/absorption/path in E/B fields/ionising ability;
connection between energy and above; 2
(ii) gamma rays take away the excess energy; 1
(iii) different energy levels (in the nucleus); 1
[5]
4. (i) An explanation to include two from:
1. high speed/energy;
2. electrons/negative particles;
3. emitted from nucleus;
4. a neutron splits;
[Accept a neutron splits into a proton and an electron
for two marks] 2
(ii) 2
[4]
5. (a) An explanation to include:
• cannot be divided / broken down further;
• electrons; 2
(b) (i) A suggestion to include:
• neutrons have no charge/cannot be deflected by E/B fields 2
• (difficult to detect) travel though matter easily;
(ii) protons and neutrons contain 3 quarks;
different combinations of up and down quarks; 2
[6]
6. (i) u – up quark;
d – down (quark);
n – neutron;
P – proton;
+ – positron; 5
(ii) Any two from:
1. quarks; 2
2. positron;
3. neutrino;
[Allow ecf from part (a)(i) for
[Deduct 1 mark for each incorrect answer after two]
[7]
7. (a) (i) same proton number, different neutron number / OWTTE; 1
(ii) A description to include:
1. N/Z = 1 (until Z = 20) for lower proton number / initially;
2. it increases (with Z); 2
(b) (i) A description to include:
1. proton / loses proton / gains a neutron; 2
2. decays into neutron + +; 2
[Accept p n + + for two marks]
[Accept up to down quark answer]
(ii) for Ta N/Z = / 1. 41;
for Hf N/Z = / 1. 44; 2
[Accept a qualitative answer which is correct]
(iii) closer to (stable) curve / line of stability / energy has been emitted; 1
(c) An explanation to include:
1. nucleus of excess energy / nucleus undergoes rearrangement /
nucleus left in excited state / nuclear energy levels; 2
2. it takes away / gets rid of / loses energy as ;
[If word nucleus does not appear – 1 mark max]
[10]
8. (a) A calculation to include:
1. 236 – 234 / 144 – 142;
[Allow 1 mark if 143–142 or 235–234 = 1n]
2. = 2; 2
(b) proton number increases by 1;
mass number stays the same; 2
[4]
9. (a) An explanation to include:
cannot be divided/ broken down further;
electrons; 2
(b) (i) A suggestion to include:
neutrons have no charge/cannot be deflected by E/M
fields; 2
(difficult to detect) travel though matter easily;
(ii) protons and neutrons contain 3 quarks;
different combinations of up and down quarks; 2
[6]
10. (a) X marked on intersection of 19-21; 1
(b) reduce the number of neutrons/increase the number of protons/ 1
- decay/ emissions
(c) Any three from:
an electron/negative charge is emitted/-; reject electron shells
number of neutrons decreases/becomes 20;
number of protons increases/becomes 20;
sensible reference to the line of stability;
(equalises number of protons and neutrons to 20 = 2marks)
(equalises protons and neutrons = l mark) 3
(loss of neutrons and gain in protons = 1 mark)
change of quark; down quark to up quark;
(d) increases (by 1);
unchanged; 2
(e) by emitting a gamma ray/electromagnetic ray/wave/radiation; 1
[8]
