Complete the following chemical equations: (i) $\mathrm{Ca}_3\mathrm{P}_2 + \mathrm{H}_2\mathrm{O} \rightarrow$ (ii) $\mathrm{Cu} + \mathrm{H}_2\mathrm{SO}_4$ (conc.) $\rightarrow$ OR Arrange the following in order of property indicated against each set: (i) $\mathrm{HF}, \mathrm{HCl}, \mathrm{HBr}$, $\mathrm{HI}$ : increasing bond dissociation enthalpy (ii) $\mathrm{H}_2\mathrm{O}, \mathrm{H}_2\mathrm{S}, \mathrm{H}_2\mathrm{Se}, \mathrm{H}_2\mathrm{Te}$, increasing acidic character.