Describe radioactive decay. In your description, include
The types of decay
Their effect on the parent nucleus
Nuclear equations as appropriate.
Important Questions on Radioactivity
A radioactive substance has a half-life of years.
Calculate the time it will take for the number of undecayed atoms in a sample to fall to one-eighth of their original number.
The table shows the activity of a radioactive sample changed as it decayed.
| Time h | |||||
| Activity counts per second |
On the grid, draw a graph of activity against time and use it to deduce the half-life of the substance.
Show your method on the graph.
The half-life is approximately .
The first column of the table shows some uses of radioactive substances.
In the second column, write the appropriate code letter or letters from the list below :
Some radiation is very penetrating.
Some radiation is readily absorbed.
Ionising radiation damages cells
Radiation is easily detected.
Radioactive substances decay at a known rate.
| Use of radioactivity | Code letter(s) |
| finding the age of an ancient object | |
| diagnosing cancer and destroying cancerous tissue | |
| sterilising medical equipment | |
| controlling the thickness of paper in a paper mill | |
| detecting smoke in the air | |
| tracing leaks from underground pipes | |
| irradiating food |
