A Football Coach in Hopes of Improving His Kicker's Performance

A football coach in hopes of improving his kicker's performance fills a 0.9 kg football with helium rather than air.Assuming that the football contains a volume of helium equal to the air it replaces at standard temperature and pressure,what change in relative weight of the football (change in weight divided by weight) is to be expected? The volume of the football is 1.6 l.

A) 1.81 × 10^-3
B) 1.42 × 10^-3
C) 1.96 × 10^-4
D) 1.01 × 10^-3