JEE Main · 2016 · 03 Apr 2016 · Offline · Hydrogen

Take the statements in turn. Water is amphoteric, able to donate or accept a proton, so it acts as both acid and base; heavy-water ice $\mathrm{D}{}_2\mathrm{O}$ is denser than ordinary water and does sink in it; and in photosynthesis water is oxidised to $\mathrm{O}{}_2$. The remaining claim is the flaw: in the liquid and the solid the hydrogen bonding in water runs between molecules, not within one molecule, so it is extensive intermolecular bonding. The statement calling it intramolecular is the false one.