Achiral and Chiral Compounds - B and D

[assaftolko]

Compounds B and D both have no chiralaty centers - but it seems to me that B has a plane of symmetry so it's achiral, and D has no plane of symmetry so it's chiral. I always thought though, that if a compound has no chiral centers then you can say with conffidence it's achiral. Is my analysis for B and D correct? And can you say anything with certeinty about a compound with no chiralaty centers?

 

[chemisttree]

It's better to think in terms of superimposability of mirror images in these cases.