Write the balanced chemical equations for the following process: (i) $\mathrm{XeF}_2$ undergoes hydrolysis. (ii) $\mathrm{MnO}_2$ is heated with concentrated $\mathrm{HCl}$. OR Arrange the following in order of property indicated for each set: (i) $\mathrm{H}_2\mathrm{O}, \mathrm{H}_2\mathrm{S}, \mathrm{H}_2\mathrm{Se}, \mathrm{H}_2\mathrm{Te}$ - increasing acidic character. (ii) $\mathrm{HF}, \mathrm{HCl}, \mathrm{HBr}, \mathrm{HI}$ - decreasing bond enthalpy