3 (a) Figure 3 shows the symbol for the nucleus of an atom of strontium-90 - Edexcel - GCSE Physics Combined Science - Question 3 - 2020 - Paper 1
Question 3
3 (a) Figure 3 shows the symbol for the nucleus of an atom of strontium-90.
(i) How many protons are in the nucleus of an atom of strontium-90?
A 38
B 52
C 90
D 12... show full transcript
Worked Solution & Example Answer:3 (a) Figure 3 shows the symbol for the nucleus of an atom of strontium-90 - Edexcel - GCSE Physics Combined Science - Question 3 - 2020 - Paper 1
Step 1
How many protons are in the nucleus of an atom of strontium-90?
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Answer
Strontium-90 has 38 protons. This is derived from the atomic number (38) indicated in the symbol for strontium-90.
Step 2
How many neutrons are in the nucleus of an atom of strontium-90?
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Answer
To find the number of neutrons, subtract the number of protons from the mass number. The mass number is 90, and the atomic number (number of protons) is 38. Hence, the number of neutrons is:
90−38=52. Therefore, strontium-90 has 52 neutrons.
Step 3
Complete the table in Figure 4.
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Answer
The mass of strontium-90 halved after one half-life (29 years), so:
At time 0: 1600 g
After 29 years: 800 g
After another 29 years (58 years): 400 g. Therefore, fill in the following:
400 g for the 58 years.
Step 4
State the scientific name for the radioactivity detector shown in Figure 5.
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Answer
The scientific name for the radioactivity detector shown in Figure 5 is a Geiger-Müller counter.
