101.
How is a leak distinguished from ordinary background?
Answer: A
Air enters in a fixed composition, so a four-to-one ratio at masses twenty-eight and thirty-two is conclusive, whereas residual background from previous samples shows no such pattern. Mass range, drift and heating behaviour are less diagnostic. Using the known composition of the contaminant to identify its source is a neat inference, and it distinguishes a mechanical fault from a housekeeping one. Framing the question as which quantity the change acts upon makes the answer follow without calculation.
Please log in or register to report this question.