A glass tube of uniform internal radius (r) has a valve separating the two identical ends. Initially, the value is in a tightly closed position. End 1 has a hemispherical soap bubble of radius r. End 2 has sub-hemispherical soap bubble as shown in figure. Just after opening the valve,

air from end 1 flows towards end 2. No change in the volume of the soap bubbles
air from end 1 flows towards end 2. Volume of the soap bubble at end 1 decreases
no change occurs
air from end 2 flows towards end 1. Volume of the soap bubble at end 1 increases