Hätten Sie am Dienstag zwischen 10-11 etwas Zeit, 'wann'/'wo'/'in der' ich anrufen könnte?
Which relative pronoun do I have to use in the question above?
Alternatives would be
and the ones proposed by chirlu.
In my opinion, the best form would be so daß (so dass in new orthography):
If you want to know when it would be the most appropriate time to call in a larger span, I’d ask one of these:
To answer the general question, the prepositions to use with Zeit as a point in time are usually zu and um and can often be used interchangeably:
For a time span, it is mostly in: