Question

CO2 forms a solid that sublimes at -78˚C at atmospheric pressure but NO2 forms a liquid that boils at 21˚C at atmospheric pressure. How does this information support that statement that CO2 is linear molecule but NO2 is a nonlinear molecule?

Answer 1

CO2 is linear, therefore it is expect to be nonpolar. Nonpolar molecules have very low interactions, they have london dispersion forces and other very weak intermolecular forces. They have low boiling points and melting points

For NO2, expect a bent molecule, that is, a dipolar molecule. It is polar, slightly negative in N and slightly positiv ein Oxygens

this dipole interaction makes other dipole-diple interaction dorces, therefore higher boiling/freezing points...