"Is the hospital far from here?"
There is no 很 because it is a question. 很 as a verb is not required in questions and negative sentences
”医院离这儿远不远？“ Marked wrong as of 2019-03-17. Should this be accepted? I did not report it due to uncertainty.
很 has a meaning of "very". If you added "很" here, it means "very far from here?"