$\begin{array}{1 1} \text{(1)Water is oxidized to oxygen during photosynthesis.} \\ \text{(2) Water can act both as an acid and as a base.} \\ \text{(3) There is extensive intramolecular hydrogen bonding in the condensed phase.} \\ \text{(4) Ice formed by heavy water sinks in normal water} \end{array} $
