Incorrect spelling

inwhich

Incorrect spelling, explanation: in which is a useful phrase, but unlike words that always appear in a certain compound and gain a separate meaning, such as workout or maybe, its meaning is not distinct enough to make it into one separate word, which is why inwhich is an incorrect spelling.


Correct spelling

in which

Correct spelling, explanation: in which is a relatively common expression used in sentences to introduce the place of something. The phrase is not popular enough, however, to merge into one word – it’s used in many contexts, and the meaning of which is clearer when the preposition can be freely changed to at or of, so in which should always stay separate.

Definition of in which:
phrase
1. a phrase used to indicate a specific place or time in a sentence
My parents are selling the house in which I grew up.
November and December are the months in which I have to pay most for heating.