Question

1. provide 3 missing symbols and 1 number

208 0 208
83 -1
18&19. place only one number from the above nuclear equations (#12 - 17) into each blank
____ gives beta radiation only
____ gives both alpha and gamma radiation

Explanation:

Step1: Identify the nuclear - decay type

The given equation represents electron capture. The general form of electron - capture is $^{A}_{Z}X+^{0}_{ - 1}e
ightarrow^{A}_{Z - 1}Y$. Here, $A = 208$ and $Z = 83$. After electron capture, the new element has $Z=83 - 1=82$. The element with $Z = 82$ is lead, $Pb$.
The complete equation is $^{208}_{83}Bi+^{0}_{ - 1}e
ightarrow^{208}_{82}Pb$.

For question 18 and 19, since the full set of equations from #12 - 17 is not provided, we can only solve question 17 for now.

Answer:

The missing symbols and number for question 17: The left - hand side element is $^{208}_{83}Bi$, the electron symbol is $^{0}_{ - 1}e$ (already given in a non - standard way as "orbital - 1" which should be $^{0}_{ - 1}e$), and the right - hand side element is $^{208}_{82}Pb$. So the three missing symbols are $Bi$, $e$ (in correct nuclear - notation form), $Pb$ and the number is $82$.