Which ion formation takes more energy: K + or Li+?

Li⁺

Explanation:

In ion formation, the ionization energy plays a very important role. To form an ion, an atom will lose or gain an electron to become charged.

The higher the ionization energy of an atom, the more the energy required to remove an electron from it to form an ion.

Ionization energy is the energy required to remove an electron from an atom. It is the readiness of an atom to lose an electron. The lower the value, the easier it is for an atom to lose an electron and vice versa.

Generally, down the group, ionization energy decreases. Since both potassium and lithium are in group 1, Li will have a higher ionization energy. It will take more energy to form Li⁺ compared to K⁺.