Under constant pressure, a small basketball pump is filled with helium, He,
gas; the helium is then forced out of a small aperture in 2 seconds. The same
pump is filled with hydrogen bromide, HBr, gas. Under the same pressure,
how long will it take to force this gas out?
No volume is listed; let's make up a volume, say 2 L for He, then the rate is (2L/2sec) = 1 L/s. Then
rate1/rate2 = sqrt(M2/M1)
1/rate 2 = sqrt(80.9/4)
solve for rate 2, then rate = 2L/sec and solve for sec. Post your work if get stuck.