Incorrect spelling

inwhich

Incorrect spelling, explanation: there are expressions in English that started out as separate words but due to being used so often became merged into one. Inwhich is not one of those words and it’s incorrect because, despite the fact that the phrase in which may be very useful, it’s not used as often as, for example, maybe, to become one word.


Correct spelling

in which

Correct spelling, explanation: in which consists of a preposition in and the relative pronoun which and is used to specify the time or place where something is located. Similarly, there are also expressions such as on which, at which or of which, depending on the context and purpose for which the expression is intended, however in which and all similar phrases are spelled separately.

Definition of in which:
phrase
1. a specification of the time or place where something is located
The times in which this castle was used by royalty are long gone.
On the left, there is storage in which we keep all cleaning supplies.