Chemical energetics: describe question

The enthalpy change of hydration, $\Delta H_{\text{hyd}}$, is defined as the enthalpy change when one mole of gaseous ions dissolves in water to form an infinitely dilute solution.

(a) Describe how the charge and the radius of an ion each affect the value of $\Delta H_{\text{hyd}}$.

(b) For the ionic compound $\ce{KCl}$, the lattice energy $\Delta H_{\text{lat}}$ is $-701\ \text{kJ mol}^{-1}$ and the enthalpy change of solution $\Delta H_{\text{sol}}$ is $+17\ \text{kJ mol}^{-1}$. Describe an energy cycle that relates $\Delta H_{\text{sol}}$, $\Delta H_{\text{lat}}$, and the enthalpy changes of hydration of $\ce{K^+}$ and $\ce{Cl^-}$ ions. Use the cycle to explain why the enthalpy change of solution has a positive value.

(c) Predict, with a reason, whether $\Delta H_{\text{hyd}}$ for $\ce{Ca^{2+}}$ is more exothermic or less exothermic than that for $\ce{K^+}$.