The correct order of atomic radii among the group 13 elements is-

1. B < Al < In < Ga < Tl
2. B < Al < Ga < In < Tl
3. B < Ga < Al < Tl < In
4. B < Ga < Al < In < Tl

AlF₃ is soluble in HF only in the presence of KF due to the formation of-

1.  ${\mathrm{K}}_3\left({\mathrm{AIF}}_3{\mathrm{H}}_3\right)$
2.  ${\mathrm{K}}_3\left({\mathrm{AIF}}_6\right)$
3.  ${\mathrm{AIH}}_3$
4.  $\mathrm{K}\left({\mathrm{AIF}}_3\mathrm{H}\right)$