Assuming the validity of Bohr's atomic model for hydrogen like ions the radius of \( \text{Li}^{++} \) ion in its ground state is given by \( \frac{1}{X} a_{0} \), where \( X = \) _____________. (Where \( a_{0} \) is the first Bohr's radius.)
\( 2 \)
\( 1 \)
\( 9 \)
\( 3 \)