Date | November 2018 | Marks available | 3 | Reference code | 18N.2.HL.TZ0.6 |
Level | Higher level | Paper | Paper 2 | Time zone | 0 - no time zone |
Command term | Calculate | Question number | 6 | Adapted from | N/A |
Question
is formed when a nucleus of deuterium () collides with a nucleus of . The radius of a deuterium nucleus is 1.5 fm.
State how the density of a nucleus varies with the number of nucleons in the nucleus.
Show that the nuclear radius of phosphorus-31 () is about 4 fm.
State the maximum distance between the centres of the nuclei for which the production of is likely to occur.
Determine, in J, the minimum initial kinetic energy that the deuterium nucleus must have in order to produce . Assume that the phosphorus nucleus is stationary throughout the interaction and that only electrostatic forces act.
undergoes beta-minus (β–) decay. Explain why the energy gained by the emitted beta particles in this decay is not the same for every beta particle.
State what is meant by decay constant.
In a fresh pure sample of the activity of the sample is 24 Bq. After one week the activity has become 17 Bq. Calculate, in s–1, the decay constant of .
Markscheme
it is constant ✔
R = «m» ✔
Must see working and answer to at least 2SF
separation for interaction = 5.3 or 5.5 «fm» ✔
energy required = ✔
= 6.5 / 6.6 ×10−13 OR 6.3 ×10−13 «J» ✔
Allow ecf from (b)(i)
«electron» antineutrino also emitted ✔
energy split between electron and «anti»neutrino ✔
probability of decay of a nucleus ✔
OR
the fraction of the number of nuclei that decay
in one/the next second
OR
per unit time ✔
1 week = 6.05 × 105 «s»
17 = ✔
5.7 × 10−7 «s–1» ✔
Award [2 max] if answer is not in seconds
If answer not in seconds and no unit quoted award [1 max] for correct substitution into equation (MP2)