CIE iGCSE Co-Ordinated Science P5.2.4 Half-life Exam Style Questions Paper 1
Question
A radioactive isotope has a half-life of 18 years. A sample contains 80 million atoms of this isotope.
How long does it take for the number of atoms of this isotope in the sample to decrease to 10 million?
A 2.25 years
B 6.0 years
C 54 years
D 180 years
▶️Answer/Explanation
Ans :A
Question
A pure sample of a radioactive substance decays. The graph shows how the number of these radioactive atoms in the sample changes with time.
What is the half-life of the substance?
A 10 s B 20 s C 30 s D 40 s
▶️Answer/Explanation
Ans : A
Question
The isotope of americium used in a smoke detector has a half-life of 430 years. A sample of this
isotope emits 36 000 particles per minute.
At which rate does it emit particles 1290 years later?
A 4500 counts per minute
B 9000 counts per minute
C 12 000 counts per minute
D 18 000 counts per minute
▶️Answer/Explanation
Ans : A
Question
The diagram shows how the count rate for a radioactive isotope varies with time.
How many half-lives of the isotope elapse in 45 hours?
A 1
B 3
C 45
D 75
▶️Answer/Explanation
Ans : B