Solution

Ionisation energy is the amount of energy, which is required to remove the most loosely bound electron(s) from an isolated gaseous atom to form a positive ion. In forming an ionic bond, one atom must form a cation by losing one or more electrons. In general, elements having low ionisation energies have a more favourable chance to form a cation, thereby having a greater tendency to form ionic bonds.
Electron affinity is the amount of energy released, when an isolated gaseous atom accepts an electron to form a negative ion. The other atom participating in the formation of an ionic compound must form an anion by gaining an electron (s). Higher electron affinity favours the formation of an anion. Therefore, generally, the elements having higher electron affinity favour the formation of an ionic bond.
Lattice energy 'is the energy released when one mole of an ionic compound in crystalline form is formed from the constituent ions'. Therefore, larger lattice energy would favour the formation of an ionic bond.