Because kaf is almost never used at the end of a word, and rarely to make the k sound in modern hebrew. Kuf is much more common. Also, because the root for this word is מ.ת.ק. Using a kaf would change the meaning as well as the pronunciation.
Why is it not correct to say התפוז הוא לא מתוק
Hebrew has no "to be". You can say התפוז הוא לא מתוק but it's weird and unnecessary and you shouldn't.
Okay, but I've seen a few instances on Duolingo of הוא or זה before an adjective, so how do I know when to use it?
The fill in the blank sentences are backward: "לא התפוז ____". Not helpful for learning hebrew.
would be nice and helpful to hear the words when selecting them
why is the final qaf not used in sweet?
because this word does not end with a qaf but with a quf and a quf does not have a final form. The qaf (khaf) is this one: כ (and final form being ך). The quf is this one: ק
The letter Khaf is never spelt with q, unlike Quf/Qof. Pay attention.
Why is not (מאתוקא)
Why should it be?
Seems like more un necessary letters
Any general rule about using tav vs yet?
Hatapúach lo matoq?
Why isn't it 'התפוז זה לא מתוק' , bc its talking about 'the' specific orange?
That would be "this orange", in formal writing, which is different from "the orange".