State one characteristic that is shared by all yttrium isotopes.
Describe how a neutral atom of Q is different from a neutral atom of yttrium-90.
A sample of yttrium-90 is placed near a radiation detector in a laboratory. No other radioactive samples are in the laboratory. A counter records the count rate. Fig. 10.1 is a graph of count rate against time. Using Fig. 10.1, determine the average background count rate.
Suggest two separate origins for the background count.
Using Fig. 10.1, determine the half-life of yttrium-90. Show how the answer is obtained.
Several of the plotted points in Fig. 10.1 are not on the best-fit line. Explain why.
A stream of beta-particles, moving through a vacuum, enters the region between two parallel metal plates. One plate is negatively charged and the other is positively charged. Fig. 10.2 shows the arrangement. On Fig. 10.2, draw the path taken by the beta-particles as they travel between the two plates.