The crystal class which is not a planar point group i8 (a) 3m (b) 4 mm (c) 3 d) 6/m

Corrected; the statement of question is confusing. If you will think about the point group without planar symmetry then answer will be 3 (which I thought earlier); but if you will ...

Planar mean it should present in 2d plane. For 6/m we need 3d space. 6/m =6 fold rotation+ perpendicular to plane c axis

Ans (D) 6/m Point group 6/m is not a planar point group because mirror plane will create a reflection of each faces lying in one plane.

2 Faculties have different answers

please dont confuse the aspirants