How do we find if a molecule is ramman active or infrared activ??

hcl is correct option..

In order for a vibrational mode to absorb infrared light, it must result in a periodic change in the dipole moment of the molecule. Such vibrations are said to be infrared active. ...

A symmetrical vibration, without change in the dipole moment would be Raman active, and not in IR. Like the stretching of a molecule of hydrogen. Water being non linear has no vibr...

Only those molecular vibrations producing a dipole–moment change are IR active, allowed in the IR, and only those molecular vibrations producing polarization of the electron cloud ...