Anhydrous aluminium chloride $(Al_2Cl_6)$ is a covalent compound and soluble in water,giving:

Electrovalent compounds are

Which of the following is an ionic compound?

Which pair will form the most stable ionic bond?

Use the following data to calculate $\Delta _{lattice}H^{\theta }$ for $NaBr$. $\Delta _{sub}H^{\theta }$ for sodium metal $= 108.4 \ kJ \ mol^{-1}$,ionization enthalpy of sodium $= 496 \ kJ \ mol^{-1}$,electron gain enthalpy of bromine $= -325 \ kJ \ mol^{-1}$,bond dissociation enthalpy of bromine $= 192 \ kJ \ mol^{-1}$,$\Delta _{f}H^{\theta }$ for $NaBr_{(s)}$ $= -360.1 \ kJ \ mol^{-1}$.

The correct order of lattice energy of the following compounds is: