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This question is about radioactivity - Edexcel - GCSE Physics - Question 3 - 2021 - Paper 1
Question 3
This question is about radioactivity. (a) Alpha (α), beta (β) and gamma (γ) are three types of radioactive emissions. Which statement describes all of these radioa... show full transcript
Worked Solution & Example Answer:This question is about radioactivity - Edexcel - GCSE Physics - Question 3 - 2021 - Paper 1
Step 1
Step 2
Describe one similarity and one difference between the numbers of particles in one nucleus of fluorine-19 and one nucleus of a radioactive isotope of fluorine.
Answer
Similarity: Both fluorine-19 and a radioactive isotope of fluorine have the same number of protons, which is 9, as they are both isotopes of fluorine.
Difference: The radioactive isotope will have a different number of neutrons compared to fluorine-19, resulting in a different mass number. For example, fluorine-18, a radioactive isotope, has 9 protons and 9 neutrons.
Step 3
Step 4
Give a reason why there would now be a reading on the counter.
Answer
When the beta source is removed, the count would drop to zero since there would be no beta particles emitted; however, if there is background radiation present, the counter would continue to register this background radiation as a reading.
Step 5
Step 6
Calculate the number of radium-223 nuclei remaining in the source after a time of 33 days.
Answer
To calculate the number of radium-223 nuclei remaining after 33 days, you first determine how many half-lives have elapsed:
33 days ÷ 11 days/half-life = 3 half-lives.
If we start with a quantity of 1.7 × 10^{23} nuclei, after 3 half-lives, the remaining nuclei can be calculated using:
Remaining nuclei = Initial nuclei × (1/2)^n where n is the number of half-lives.
Remaining nuclei = 1.7 × 10^{23} × (1/2)^3 = 1.7 × 10^{23} × (1/8) = 2.125 × 10^{22} nuclei remaining.