In what case and why is letter 'o' pronounced as 'ʌ' like in the word 'cut' /kʌt/?
- Done is pronounced /dʌn/ while other words of the kind are pronounced differently: lone, bone, tone.
Why is gone pronounced /ɡɒn/?
Why is gone spelled the same way as lone, when it's pronounced differently?
Because when English spelling was fixed, they were pronounced the same.
In Middle English, there was no fixed spelling of words. The spelling became fixed shortly after Shakespeare wrote.
Shakespeare treats the following words as if they all rhyme in his poems and sonnets:
The same sound change that affected on and gone seems to have also affected shone; it rhymes with gone in the U.K. and lone in the U.S.
On the other hand, this explanation doesn't work for the word done. The only rhymes Shakespeare has for done is sun (which he uses several times), begun, and run. My unsupported speculation would be that the sound of done changed sometime during Middle English, but the spelling was kept done because the root word is do.
English is a mixing pot of other languages.
They have words from Latin, French, Dutch and many other langauges.
This is partially because of England's history of being conquered. Th influx of emmigrants also influenced the language.
The Norman invasion of England gave the english langauge words like beef (from the French word for cow), pork (from the French word for pig) and mutton (from the French word for sheep).
(Ivanhoe has a comical explanation of this in its first chapter.)
Dutch immigrants gave the English language many of its kn words, infact reading Chaucer's old english is much easier with a knowledge of the Dutch langauge.
(i.e. Chaucer's use of eek meaning also is a derivitave of the Dutch ook meaning the same thing.)
The Roman invasion will have contributed Latin words as did the fact that the langauge of Catholic bibles etc. was Latin.
Botanical names are in Latin to this day. Many scientific words and terms have different pronounciations because they have latin and greek origins.
Words starting or having a ph in them are often scientific and have Greek origins. (Thanks to comments.)
The invasion by the Norse has influenced the English langauge as well and this can be heard especially is some Northern England dialects.