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Two spherical soap bubbles in vacuum are connected through a narrow tube. Radius of left bubble is R0  and that of right bubble is 2R0. Air flows from one side to another very slowly maintaining spherical shape of bubbles . At any instant before steady state is reached,  r1,  A1,  V1,  n1 are radius, surface area, volume and number of moles of gas in the left bubble and  r2,  A2,  V2,  n2 are radius, surface area, volume and number of moles in the right bubble. Assume that temperature T remains constant throughout the process. Let  n1=2 initially and S be the surface tension of soap solution. Choose the correct option(s). (R is universal gas constant)

a
Air flows from right to left bubble
b
The total film area of both the bubbles is 15 RTS
c
If, at an instant number of moles in left bubble is 1, then r1=R02
d
If, at an instant number of moles in left bubble is 1, then r2=3R02

detailed solution

Correct option is C

At any instant the total number of moles  n1+n2=n remains constant Also, n1n2=P1V1P2V2=4Sr1×43πr134Sr2×43πr23=r1r22=14∴n1+n2=2+8=10=constantP1V1+P2V2=nRT⇒4Sr1×43πr13+4Sr2×43πr23=10RT⇒A1+A2=7.5RTS=Total Surface Area is constant When, n1=1⇒n2=9∴r1r22=19⇒r2=3r1; Also, since, total surface area is constant Initial surface area=Final surface area⇒4πR02+4π4R02 =4πr12+4πr22⇒r12+r22=R02+4R02=5R02∴r12=110×5R02⇒r1=R02⇒r2=3R02

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