Figure 8 shows the symbol for the nucleus of an atom of strontium-90 - Edexcel - GCSE Physics - Question 5 - 2020 - Paper 1
Question 5
Figure 8 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 ... show full transcript
Worked Solution & Example Answer:Figure 8 shows the symbol for the nucleus of an atom of strontium-90 - Edexcel - GCSE Physics - Question 5 - 2020 - Paper 1
Step 1
How many protons are in the nucleus of an atom of strontium-90?
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Answer
Strontium (Sr) has an atomic number of 38, which indicates that it has 38 protons in its nucleus. Therefore, the answer is 38.
Step 2
How many neutrons are in the nucleus of an atom of strontium-90?
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Answer
To calculate the number of neutrons, use the formula:
Number of neutrons=Mass number−Atomic number
For strontium-90:
Number of neutrons=90−38=52
Thus, there are 52 neutrons in the nucleus.
Step 3
Complete the table in Figure 9.
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Answer
In 29 years, the mass of strontium-90 decreases from 1600 g to 400 g. This suggests that the mass halves every 29 years (the half-life). Completing the table, we have:
mass of strontium-90 in g
time in years
1600
0
800
29
400
58
Step 4
State the scientific name for the radioactivity detector shown in Figure 10.
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Answer
The scientific name for the radioactivity detector is 'Geiger-Müller counter'.
