Gram - atomic mass = mass of `6.022 xx 10^(-23)` atoms = mass of 1 atom `xx 6.022 xx 10^(-23)`
`= (3.15 xx 10^(-23) g) xx 6.022 xx 10^(23) = 3.15 xx 6.022 g = 18.97 g`
`therefore` atomic mass of the element = 18.97
Thus , the element is most likely to be fluorine .