Physics igcse Half-life project

Radioactive iodine-131 emits beta particles and has a half life of 8 days. it decays to produce xenon-131.

Which statement about this decay is correct?

• After 16 days the number of iodine-131 has reduced to one eighth

• After 8 days the number of xenon-131 atoms has halved.

• after 16 days the iodine-131 has decayed completely.

• After 16 days the number of iodine-131 has reduced to one quarter.

The half life of a radioactive substance is 5 hours. The background radiation is 20. A sample was tested and the total radiation was 150.

How much of the substance was present after 15 hours.

• 18.75

• 16.25

• 21.25

• 23.75

A radioactive substance was tested to contain 240 g.The half life of the substance is 50 years. How much of the substance will be left after 2400 months.

• 15

• 30

• 7.5

• 60

The half-life of a radioactive substance is 5 hours. A sample is tested and found to contain 0.48 of the substance.

How much of the substance was present in the sample 20 hours before the sample was tested

• 0.003

• 0.12

• 1.92

• 7.68

A radioactive source produces a count rate on a detector of 1600 counts / s. After 32 hours the count rate has fallen to 100 counts / s. Both count rates have been corrected for background radiation. What is the half-life of the source?

• 4

• 6

• 8

• 12