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
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 128
(ii... show full transcript
Worked Solution & Example Answer: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
The number of protons in the nucleus of an atom is represented by the atomic number. For strontium-90, this is indicated as 38 in the notation 3890Sr. Therefore, the correct answer is A 38.
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, we can use the formula:
extNumberofNeutrons=extMassNumber−extAtomicNumber
For strontium-90:
90−38=52
Thus, the number of neutrons is B 52.
Step 3
Complete the table in Figure 4.
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Answer
To complete the table:
The initial mass is 1600 g at time 0 years.
After one half-life of 29 years, the mass of strontium-90 will halve:
ext{Mass after 29 years} = rac{1600}{2} = 800 g
The next halving after an additional 29 years will give:
ext{Mass after 58 years} = rac{800}{2} = 400 g
Thus, the completed table is:
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 5.
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Answer
The scientific name for the radioactivity detector shown in Figure 5 is a Geiger-Müller (GM) counter.
