How do I know when a word with "ch" is pronounced hard or softly?

Solution 1:

There is no hard-and-fast rule to indicate when ch is hard or soft, unfortunately.

The main difference is in the origin of the word. English is a melting pot of many different languages: Latin, French, German, Scandinavian languages, you name it. In general, words originating from French will have a soft ch:

Parachute, cache, attache

Words originating from Germanic languages will have a hard ch:

Church, bench

However, even this isn't foolproof because many French-origin words have been hardened:

Bachelor, channel, charm

I would say that there are considerably more hard ch words than there are soft.