for \$\\text{Pu-238}\$:\n\n\\[ ^{238}_{94}\\text{Pu} \\]\n\nMatch each property of this nucleus with its correct numerical value.\n* Properties: **Mass number**, **Number of protons**, **Number of neutrons**\n* Values: **94**, **144**, **238**","markscheme":"- Mass number = 238 B1\n- Number of protons = 94 B1\n- Number of neutrons = 144 B1","marks":3,"order":0,"markingRubric":null,"explanation":null,"options":[]},{"id":"fc685770-e197-4639-a58f-7e1de65956e5","label":"b","content":"A physicist measures the background-corrected counts per minute (cpm) of a sample of \$\\text{Pu-238}\$ five different times.\n\nTable 1 shows their results:\n\n| Measurement | 1 | 2 | 3 | 4 | 5 |\n| :--- | :---: | :---: | :---: | :---: | :---: |\n| **Count rate (cpm)** | 425 | 418 | 425 | 431 | 422 |\n\nWhat is the **mode** of the count rate measurements?\n\nMode = ............................................................ cpm","markscheme":"- Mode = 425 cpm B1","marks":1,"order":1,"markingRubric":null,"explanation":null,"options":[]},{"id":"26e91760-f44b-46b1-a31f-0ce6c4e388e9","label":"c","content":"An alpha particle is emitted by \$\\text{Pu-238}\$. Complete the radioactive decay equation for this decay:\n\n\\[ ^{238}_{94}\\text{Pu} \\rightarrow ^{234}_{\\dots\\dots}\\text{U} + ^{\\dots\\dots}_{2}\\text{He} \\]","markscheme":"- Lower blank (atomic number of $\\text{U}$) = 92 B1\n- Upper blank (mass number of helium) = 4 B1","marks":2,"order":2,"markingRubric":null,"explanation":null,"options":[]},{"id":"8b7a7068-eeb0-4e74-b7e4-56b49c839b30","label":"d","content":"A student says, 'Beta radiation is more dangerous than alpha radiation.'\n\nDo you agree with this student? Explain your answer with reference to ionising and penetrating power.","markscheme":"- Evaluates statement: either \"Agree\" or \"Disagree\" with appropriate context B1\n- Compares penetrating power: Beta is more penetrating than alpha (or alpha is stopped by dead skin/paper, while beta penetrates several millimetres of body tissue) B1\n- Compares ionising power: Alpha is much more highly ionising than beta (so alpha causes far more localized cellular/DNA damage if inside the body) B1","marks":3,"order":3,"markingRubric":null,"explanation":null,"options":[]},{"id":"4847d422-866f-4078-880f-ae7347188eed","label":"e","content":"A laboratory technician is using a radioactive element. They accidentally inhale some radioactive dust containing \$\\text{Pu-238}\$ and become **contaminated**.\n\nThe technician immediately washes their skin and leaves the laboratory.\n\nExplain why the technician is still at risk.","markscheme":"- Explains that the technician is contaminated internally because they inhaled the dust / the radioactive isotope is inside their lungs B1\n- States that the source cannot be washed off internally, so it continues to emit alpha particles directly into delicate internal tissues, causing severe cellular damage, mutations, or cancer risk B1","marks":2,"order":4,"markingRubric":null,"explanation":null,"options":[]},{"id":"4d5745d2-d051-472a-94ea-75686ed80b55","label":"f","content":"\$\\text{Pu-238}\$ is commonly used to generate heat in radioisotope thermoelectric generators (RTGs).\nThe thermal power output generated increases linearly with the mass of \$\\text{Pu-238}\$.\n\nThis is a graph of thermal power output against mass of \$\\text{Pu-238}\$:\n\n![Graph showing Thermal Power Output against Mass of Plutonium-238](https://assets.mathsgenie.co.uk/aqa-qb/8d2010b5-61d0-43fa-8ac5-d1bf5869fd8c.png)\n\nUse the graph to find the mass of \$\\text{Pu-238}\$ needed for a thermal power output of 0.28 kW.\n\nMass = ............................................................ kg","markscheme":"- Finds mass = 0.50 kg (allow 0.49 to 0.51 kg) B1","marks":1,"order":5,"markingRubric":null,"explanation":null,"options":[]},{"id":"11520f3e-c301-43aa-ad68-67166cbf98aa","label":"g","cont

Time (minutes)	Activity (counts per second)
0
5
10
15	118
20	100
25	83
30	70
35	59
40	50
45	41
50	35
55	29
60	25

Time (minutes)	Activity (counts per second)
0
5
10
15	118
20	100
25	83
30	70
35	59
40	50
45	41
50	35
55	29
60	25

Radioactive emissions

Question 5

Radioactive emissions Questions

Radioactive emissions

Question 5

Radioactive emissions Questions