Two soap bubbles, each with a radius 'r' coalesce in a vacuum under isothermal conditions to form a bigger bubble of radius R. Then R is equal to :

Options

A. `2^(-1//2)r`
B. `2^(1//3)r`
C. `2^(1//2)r`
D. `2r`

Answer

C

Explanation

Under isothermal conditions there is no change in surface area
`therefore4pir^(2)+4pir^(2)=4piR^(2)`
`rArrR=sqrt2r`
Hence the correct choice is (c).