This is a very subjective question as it depends on the comfort level of the student who appears for the UPSC examination.If the person with BSc degree is very thorough and comfortable with their subjects then they can clear IAS examination. There are many examples in the past who have been successful in securing IAS after BSc degree.
You can read about the Science & Technology Questions in UPSC Mains GS-3 in the given link.
Further readings:
Comments