1. Who made the cake?

Question

2. By whom was the cake made?
3. Whom was the cake made by?
(Which one is the passive voce sentence of #1?)

4. What made you angry?
5. By what were you made angry?

6. Who bought the pen?
7. By whom was the pen bought?

(Is each pair grammatical? Is each odd number grammatical?)

Answer 1

#2 is the passive of #1.

The other two pairs are worded fine. Nice job.