How much nitrogen can be obtained from 40 liters of air if its volume fraction is 0.78?

to find the volume of nitrogen from air, with a volume of 40 liters, if you know its volume fraction = 0.78, you need
the volume of air multiplied by its volume fraction, that is, we get
V (N 2) = V air * volume fraction
V (N 2) = 40 liters * 0. 78 = (40 * 0.7 + 40 * 0.8) liters = (28 + 40 * 0.08) liters = (28 + 3, 2) liters = (28 + 2 + 1, 2) liters = ( 30 + 1, 2) liters = 3 1. 2 liters
as a result, we got that the volume of nitrogen from 40 liters of air = 3 1, 2 liters
answer 6 31, 2 liters