How does one correctly apply "in which", "of which", "at which", "to which", etc? I'm confused with which one to apply when constructing sentences around these. Please help me out here.
The trick to knowing how to use; of which, at which, in which, to which, from which is to analyse the prepositional phrases, phrasal verbs, verbs and prepositions:
- He /spoke of/ war and peace and many other topics that day.
The topic /of which he spoke/ was complex.
The verb here that means to speak about a topic is /to speak/ of a topic/: to mention
- The party /at which/ he spoke/ was noisy.
Phrase: A party is held /at a place/. It is implied.
- The situation /in which/ we found ourselves was dire.
Phrase: /to find oneself /in a situation.
- The bonds /from which/ we broke free were tight.
phrase: to /break free/ from bonds.
- The town /to which/we were driving was 50 ks away.
phrase: to /drive/ to a place.
Summary (and not a complete answer but a general one): The preposition depends on the verb that takes a preposition, a phrasal verb that includes a preposition, or it depends on the prepositional phrase used. Also, there are many other prepositions that can be paired with which: under, during, about, over, etc.
Probably easiest to explain through examples. Each phrase simply means "the thing that we've already mentioned", e.g.
The box in which the books are kept
The town of which we were speaking
The time at which we will arrive
The destination to which we were heading
I'm sure there's a grammatically-correct term, but they're really just the correct forms of "the box the books are kept in"/"the town we were speaking of", i.e. removing the trailing preposition.