also: このなか
of these; among these; between these
Refers to a choice, number, subset, or comparison within a set already mentioned. このうち is common for a counted set; この中で can also mean “among this group.”
There are five candidates. We will choose two of them.
この中で一番好きな写真を選んでください。
Please choose the photo you like best from these.
in here; inside this; in this
Only when written この中 · Only with reading このなか
Used with この中 read このなか for something physically or conceptually inside the thing or space being indicated.
鍵はこの中に入っています。
The key is in here.
この内 means "among these (items just mentioned)", while そのうち usually means "before long/soon" though it can also mean "among those" in the same set-reference sense.
Kanji spelling for このうち; understandable and attested, but the expression is often written in kana.
Common spelling and reading for “inside this” and also for “among this group,” especially in この中で.
Attested reading, but この中 is normally read このなか; use このうち or この内 when the intended reading is このうち.
A transparent phrase from この (“this”) plus うち/内 (“inside; within; among”). The spelling この中 uses 中, emphasizing “inside” or “within this.”