The solid phosphorus pentachloride exists as:

$X$ melts at a low temperature and is a bad conductor of electricity in both liquid and solid states. $X$ is:

Which of the following has the highest melting point?

The lattice enthalpy of an ionic compound is the enthalpy change when one mole of an ionic compound in its solid state dissociates into its ions in the gaseous state. It is impossible to determine it directly by experiment. Suggest and explain an indirect method to measure the lattice enthalpy of $NaCl_{(s)}$.

Which of the following exhibits the weakest intermolecular forces?

Carbon dioxide is a gas while silica is a solid because .......