“i know how excited you were to be offered the new job. it’s too bad the hours aren’t what you were expecting. talking to your new boss about your hours before you accept seems like a good idea.” what makes this an effective response? is there anything you would change or add?  

This is an effective response because it is sincere and it depicts that the person had a good decision in talking things out with the boss. It depicts the emotion of being disappointed of the final decision of the hours, it is also the proper way of responding to a person who is sad.

I believe the line from this passage that describes the changed feelings of the narrator is "All that had so long engaged my attention suddenly grew despicable."

Explanation:

The narrator, Victor Frankenstein, is describing, in this passage, the change of feelings he has undergone concerning his work. According to him, he is no longer interested in natural history, seeing it as a "would-be science" that cannot bring any "real knowledge". He went from being excited about it to disdaining it completely. That's why he took up to working with mathematics and its "secure foundations". The line that best describes the changed feelings is, "All that had so long engaged my attention suddenly grew despicable."