Angstroms is defined as a unit of length equal to one hundred-millionth of a centimeter, 10–10 meter, used mainly to express wavelengths and inter atomic distances.
Angstroms is a unit used for 10^-10
It means that one meter will have 10^10 Angstroms or
1 Angstroms = 10^-10 meters
the given radius of barium atom is 2.22 X10^-10 m
This will be equal to 2.22 Angstroms.