State the values of X and Y that appear in the symbol $^{X}_{Y}\text{Pa}$.\n\nX = ....................................................\n\nY = ....................................................
Complete the equation for the decay of a protactinium nucleus.\n\n................ Pa $\rightarrow$ $^{0}_{-1}\beta$ + ............... U
Suggest two sources of background radiation that occur naturally.\n\n1. ..............................................................................................................\n\n2. ..............................................................................................................
Predict a value for the count rate measured 1200 minutes later.\n\ncount rate = ....................................................
Suggest one reason why the count rate measured 1200 minutes later may be slightly different from the value predicted in (b)(ii).