cancels/balances (charge) on electron accept positive (charges) cancel out the negative(charges) neutrons have no charge is neutral do not accept total charge of protons, electrons (and neutrons) is 0 unless qualified 1 (c) (i) (3) fewer neutrons accept lower/ smaller mass number do not accept different numbers of neutrons any mention of fewer/more protons/electrons negates mark accept answers in terms of U- 238 providing U -238 is specifically stated i.e. U -238 has (3) more neutrons 1 (ii) neutron 1 (iii) (nuclear) fission accept fision do not accept any spelling that may be taken as fusion 1  Page 30 of 34
M9. (a) proton all 3 in correct order electron allow 1 mark for 1 correct do not neutron accept letters p, e, n 2 (b) 9 reason only scores if 9 is chosen 1 number of neutrons and protons 1  M10. (a) X emits beta accept β 1 Y emits alpha, beta, gamma must have all three accept α , β , γ 1 (b) gamma accept beta and gamma any mention of alpha loses first mark 1 radiation can penetrate (the plastic) 1 kills bacteria or microbes or micro-organisms or viruses not germs 1  M11. (a) (i) L 1 (ii) M 1 (b) To make a smoke detector work. 1 Page 31 of 34
(c) 40 no tolerance 1  M12. (a) all 3 correct Gamma source Beta source Alpha source allow 1 mark for one or two possible links no marks for more than one line from a source or to a box 2 (b) (i) geiger - müller (tube) accept G-M (tube) accept geiger tube or geiger counter 1 (ii) steady line rising then falling at leak must be one peak only 1 (c) (i) can penetrate (skull or head) accept goes through body accept most penetrating do not accept strongest do not accept can penetrate skin 1 (ii) cancer cells receive full dose or more radiation accept healthy cells not damaged 1 healthy or other cells receive low dose only do not accept it is safer 1 Page 32 of 34
(iii) any two properties from: • travel through a vacuum do not accept they are an energy form • travel at same speed in air or vacuum • can be diffracted treat as a list ignoring 1 and 2 • can be reflected • can be refracted • travel in straight lines • all transverse • can be polarised • transfer energy 2  Page 33 of 34
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- Fall '19
- Proton, Ionizing radiation, accept α