None of them are truly correct, as Arabic is written with the Arabic alphabet. Edit: Ok, I don’t have my Arabic dictionary with me, and I’m seeing dueling spellings for the word. Does anybody else know if the first letter is a khaa or a kaaf?
There’s no official transliteration scheme for Arabic, but as long as you are able to differentiate between letters that are distinct in Arabic but sound similar to English speakers, you should be alright.
That’s the spelling that Wehr and Cowan’s Arabic dictionary has for it: kaaf, not khaa.
There’s no unique “official” scheme, but there are several recognized standard schemes. In the ALA-LC Arabic romanization system, which is probably the most commonly used strict transliteration system, "??? " would be represented with the characters “a”, “l”, hyphen, “k”, “i” with a macron, “m”, “i”, “y”, “a” with a macron, apostrophe.
[Edit: Hmm, how do I get yBeayf’s Arabic properly reproduced in a quote?]
That would indicate the second one is right, i.e. that it’s spelled with kaaf instead of khaa, as is confirmed by Wehr per Kimstu. Someone should correct the Wikipedia article on Alchemy.