An Air Sample Is Contaminated With $15 \mathrm { O }$

Multiple Choice

An air sample is contaminated with $15 \mathrm { O }$ , which has a half-life of $2.03$ minutes. You can pass it through a long pipe to allow it to decay until it can be safely released into the atmosphere. If the speed of the gas in the pipe is $1.1 \mathrm {~m} / \mathrm { s }$ , how long must the pipeline be for the sample to decay to $3.0 \%$ of its original activity?

A) $8.0 \mathrm {~m}$
B) $250 \mathrm {~m}$
C) $680 \mathrm {~m}$
D) $72 \mathrm {~m}$