Chemistry - Solid State Question with Solution | TestHub

NaCl and ${\mathrm{H}}_2\mathrm{O}$ are diamagnetic substances because all their electrons are paired.

${\mathrm{O}}_2$ is a paramagnetic substance due to the presence of two unpaired electrons in its antibonding molecular orbitals.

${\mathrm{CrO}}_2$ is a ferromagnetic substance. It is strongly attracted by a magnetic field and can be permanently magnetized. It is widely used in making magnetic tapes for audio recording.

Answer: ${\mathrm{CrO}}_2$