Which of the following are endothermic process?

When an electron is added to a monovalent anion to create a divalent anion, the reaction ${\mathrm{S}}^{-}\left(\mathrm{g}\right)\to {\mathrm{S}}^{2-}\left(\mathrm{g}\right)$ constitutes an endothermic step since the energy is absorbed.

Since it takes energy to remove an electron from a deposited ion, the reaction ${\mathrm{Al}}^{2+}\left(\mathrm{g}\right)\to {\mathrm{Al}}^{3+}\left(\mathrm{g}\right)$) is an example of an endothermic reaction.
It stands for the third ionisation potential of aluminium.

Similarly $\mathrm{NaCl}\left(g\right)⟶{\mathrm{Na}}^{+}\left(g\right)+{\mathrm{Cl}}^{-}\left(g\right)$ is also  endothermic process.