25cm³ of a mixture of noble gases was obtained from air after the removal of other constituents. What was the original volume of air?

A. 2,500 cm³
B. 1250 cm³
C. 125 cm³
D. 80 cm³

Correct Answer:

Option A – 2,500 cm³

Explanation

Percentage of noble gases in air is 1%
25 = (1/100) X T
∴ T = 25  100 = 2500 cm³