A bubble of radius r is made of a soap solution at one end of a long capillary tube,  other  end of which is closed. Assuming Air is non-viscous and its flow in the capillary is  laminar and the process is slow enough to regard it a quasi-static one and disregard  effects of viscosity and time required for liquid in the wall of the bubble to readjust its shape, 

time interval taken to deflate the bubble (through a small opening at other end of  capillary tube) from an initial radius  ${\text{R}}_0$ to a final radius R is proportional to  ${R_0}^n-R^n$ ,  then n is  _____