Lattice enthalpy and enthalpy of solution of NaCl are 788 kJ mol^–1, and 4 kJ mol^–1, respectively.
The hydration enthalpy of NaCl is :

Reaction of ammonia with excess Cl₂ gives :

Which one of the following polymers is not obtained by condensation polymerisation?

An element crystallises in a face-centred cubic (fcc) unit cell with cell edge $$a$$. The distance between the centres of two nearest octahedral voids in the crystal lattice is :