Radioactivity Decay (Edexcel A Level Physics): Exam Questions

A detector is placed 30 cm from a gamma source, the count rate is 64 counts per minute.

The detector is then placed 60 cm from the source.

The background rate is presumed to be a constant 24 counts per minute.

Which of the following gives the expected counts per minute?

The radium isotope ${}_{88}{}^{226}\mathrm{Ra}$ is unstable and undergoes a series of $\alpha$ and ${\beta }^{-}$ emissions until a stable isotope of lead ${}_{82}{}^{206}\mathrm{Pb}$ is formed.

Which of the following nuclear equations correctly shows the number of $\alpha$  and ${\beta }^{-}$ emissions?