The ionic bonds in are formed when:
Electron affinity of Y is high and ionisation energy of X is low
Electron affinity of Y is low and ionisation energy of X is high
Lattice energy of XY is low
None of these
Ionic bonds are only possible when X can easily lose electrons and Y can accept
electrons easily i.e, ionisation energy of X should be low and electron gain enthalpy of
Y should have high negative value.
Hence Option 1 is correct.