The compound which has molecular nature in gas phase but ionic in solid state is

The compound which has molecular nature is gas phase but ionic in solid state is :

The compound which has molecular nature is gas phase but ionic in solid state is :

The compound which has ionic nature in solid state is

The compound is covalent in gaseous state but ionic in solid state is.

The compound is covalent in gaseous state but ionic in solid state is.

The compound which has linear anion in its solid state is

Name the compounds of group-15 elements which are covalent in the vapour state but ionic in the solid state.

PCI_5 is ionic in nature in solid state. Why?