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As far as I can recall there are just a few words in the English language which end with the spelling -tion after an 'S' which have a pronunciation ending as 'chan'. But in South Asia, 99% of the people pronounce such words as 'shan'.
I am referring to words like digestion, suggestion, combustion, congestion, indigestion, exhaustion, etc.
But people pronounce the word question correctly as 'chan'.