Answer
$^{45}Ti\rightarrow \,^{45}Sc+\text{positron}$
Work Step by Step
a Positron is a positively charged electron. Positron emission leads to a unit decrease in the atomic number. Therefore, the missing product has an atomic number of one less than that of $Ti$.
That is, Z= (Z of $Ti$)-1=22-1=21.
The element with atomic number 21 is scandium ($Sc$).
There is no change in mass number as the mass number of a positron is 0.
Therefore, the missing product is $\,^{45}Sc$.
