There is no such thing as an AC Generator, if its a generator, its DC. I think you are talking about an AC Alternator, in which case the answer would be -wrong answer, deleted-
As the distance between two charged objects increases, the strength of the electrical force between the objects <em>decreases</em>.
We know, the ideal gas equation,
P1V1 / T1 = P2V2 / T2
Here, P1 = 760 mm
V1 = 10 m3
T1 = 27 + 273 = 300 K
P2 = 400 mm Hg
T2 = -23 + 273 = 250 K
Substitute their values,
760*10 / 300 = 400 * V2 / 250
25.33 * 250 = 400 * V2
V2 = 6333.333/ 400
V2 = 15.83
In short, Your Answer would be approx. 15.83 m3
Hope this helps!