AlF3 is soluble in HF only in the presence of KF. It is due to the formation of
K3[AlF3H3]
K3[AlF6]
AlH3
K[AlF3H]
is insoluble in
, this is due to strong H- bonding in
,
ions are not present to form complex with
but on the addition of a small amount of
, the complex formation takes place.
Hence, the correct answer is option 2.