IGCSE Physics (0625) Unit 5. Atomic physics-5.2.4 Half-life Paper 1

Question

An explosion in a nuclear reactor spread the isotope caesium-137 across a large area.

Ninety years after the explosion, the quantity of caesium-137 present will be 12.55%of its original level.

What is the half-life of caesium-137?

A 11.25 years

B 22.5 years

C 30.0 years

D 45.0 years

Answer/Explanation

Ans: C

Question

A reading is taken every 10 minutes of the number of emissions per second from a radioactive source. The table shows the readings.

time / min

number of emissions per second

0

800

10

560

20

400

30

280

40

200

50

140

60

100

What is the half-life of the source?

A 10 min

B 20 min

C 40 min

D 60 min

Answer/Explanation

Ans: B

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