Question

Among the molecules I2, HBr, CO2, CS2, NO, identify those which are microwave active, justify the answer

Answer 1

Out of all the options given, HBr ( Hydrogen bromide) and NO ( nitric oxide) are microwave active molecules.

The important criteria for being a microwave active molecule is dipole moment. It is necessary for a particular molecule to have a permanent dipole moment for it to get a rotational spectrum and be microwave active.

Homonuclear molecules such as I2 are not microwave active, CO2 and CS2 have net zero dipole moment as their charges are distributed equally. Hence, only HBr and NO qualify as proper microwave active molecules.