Comparatively, size of `Li^o+` ion is very small with' respect to other alkali meta) ions but it moves through a solution less rapidly than the others. Justify

Beryllium salts can never have more than 4 molecules of water of crystallisation, i.e., it can never achieve coordination number > 4 while other metal ions tend to have a coordination number of 6, e.g., [Ca(H_2O)_6]^(2+) . Explain.