Discuss the stereochemistry of following reactions `:`

Explanation

[Hint]
In (i) reaction , -O-H bond of alcohol is broken and the configuration of product around chiral carbon is retained. In (ii) reaction, first step involves decomposition of `-O-H` bond,in the second `-C-O-` bond is broken. In this reaction, inversion of configuration takes place. Tosly group is better leaving group hence (C-O) bond is broken.