Among the following species, identity the isostructural pairs NF₃, $$NO_3^-$$, BF₃, H₃O⁺ , HN₃

A mixture of ideal gas is cooled upto liquid helium temperature (4.22K) to form an ideal solution

The following compounds have been arranged in order of their increasing thermal stabilities. Identify the correct order
K₂CO₃ (A), MgCO₃ (B), CaCO₃ (C), BeCO₃ (D)

Explain the difference in the nature of bonding in LiF and LiI.