Answer:
100% increase.
Explanation:
At constant temperature we have the relation
P1V1 = P2V2 where P and V are pressures and volumes, so here we have, say
P1 = 10, P2 = 1/2* 10 = 5 , V1 = 10 , V2 = ?
10 * 10 = 5 * V2
V2 = 100/5 = 20.
The original volume was 10 so the volume has doubled.
