Relationship b/w closure and decidability?

Question

Is there any relationship b/w closure and decidability?

Thanks

Comments

No, there isn't any direct relation between them.

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@goxul Eg. we say that intersection of 2 CFL's is CFL, is undecidable cause CFL's are not closed under intersection. What do we mean by this statement? 

PS: I understand that CFL's are not closed under intersection cause of egs. like a^n^b^nc^m intersection a^mb^nc^n

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When a set operation is closed it means the result is of that set only -- decidability becomes trivial.

Now when the set operation is not closed, result can be either the same set or outside of it. Deciding this becomes non-trivial. It may or may not be undecidable.