Question

what element should go in the empty box in this equation?
79
33 as → 0
-1 β +□
79
34 se
79
32 ge
selenium - 79
germanium - 79
75
31 ga
83
35 br
gallium - 75
bromine - 83

Explanation:

Step1: Balance the atomic number

In a nuclear reaction, the sum of atomic numbers on both sides must be equal.
The atomic number of \(As\) is \(33\), and for \(\beta\) particle (\(_{-1}^0\beta\)), let the atomic number of the unknown element be \(Z\).
So, \(33=- 1+Z\), then \(Z = 33 + 1=34\).

Step2: Balance the mass number

The mass number of \(As\) is \(79\), and for \(\beta\) particle (\(_{-1}^0\beta\)), let the mass number of the unknown element be \(A\).
Since \(79=0 + A\), then \(A = 79\).
The element with atomic number \(34\) is \(Se\) (selenium) and mass number \(79\).

Answer:

Selenium - 79 (the first option)