Not all questions can be answered in a way that offers Bible verses as evidence. In fact, not all questions can be answered at all. There are many things we human simply don't know the answer to, because God hasn't told them to us, and there are also many things in life that have answers that don't involve the Bible at all, like how to solve the quadratic equation or where to find the gas station with the cheapest gas or how to make chop suey.
I think it is important to point these things out when dealing with the "Where is that in the Bible?" mentality.
It is also important to point out that, even when dealing with questions that do involve theology, we are Catholics and therefore do not need to provide answers within the confines of sola Scriptura.
As Catholics, we draw information from and our theology is shaped by not only Scripture but also Tradition, the formulations of the Magisterium, philosophy, human nature (i.e., natural law) reasoning, etc.
From Jimmy's blog entry, Prayer for the Dead