The pronunciation of "CH" as "k" can be traced back to the historical development of the English language and its interactions with other languages. The English language has borrowed words from various sources, including Latin, Greek, French, and Old English, which have influenced its spelling and pronunciation patterns.
The pronunciation of "CH" as "k" is mainly seen in words of Greek origin. In Greek, the letter combination "CH" (chi) was pronounced as a voiceless velar fricative, similar to the "ch" in the Scottish word "loch" or the German word "Bach." When these Greek words were borrowed into English, their pronunciation was adapted to fit the English phonetic system.
Over time, the pronunciation of "CH" changed in English, and it began to be pronounced as a voiceless palatal fricative, like the "ch" in "cheese" or "church." However, some words of Greek origin retained the original "k" sound for "CH" due to their traditional pronunciation or etymology. Examples of such words include "chorus," "chaos," and "character."
It's important to note that English has a complex spelling system, and there are many exceptions and inconsistencies in its pronunciation rules. The pronunciation of "CH" as "k" in certain words is just one of many irregularities that exist in the language.