AAI ATC Junior Executive 25 Mar 2021 Shift 3 Paper

'Two spherical soap bubbles of radii r₁ and r₂ coalesce to form a bubble of radius R. If the surface tension of soap solution is T, atmospheric pressure is P, the change in volume of the air enclosed is V and the change in surface area is 'A'. Complete the expression using above statement, 3PV + ___ = 0