The work done in blowing a soap bubble of radius $0.2\, m$ is (the surface tension of soap solution being $0.06\, N/m$).

If $W_1$ is the work done in increasing the radius of a soap bubble from $r$ to $2r$ and $W_2$ is the work done in increasing the radius of the soap bubble from $2r$ to $3r$, then $W_1: W_2=$

$A$ spherical drop of liquid splits into $1000$ identical spherical drops. If $E_1$ is the surface energy of the original drop and $E_2$ is the total surface energy of the resulting drops,then $\frac{E_1}{E_2} = \frac{x}{10}$. The value of $x$ is:

Fill in the blanks:
$(i)$ If the molecules of a body repel each other,then the surface area ...... and the surface energy ...... (choose between 'increases' or 'decreases').
$(ii)$ If the molecules of a body attract each other,then the surface area ...... and the surface energy ...... (choose between 'increases' or 'decreases').

$n$ drops of a liquid,each with surface energy $E$,join to form a single drop. Which of the following statements is correct?

If the surface tension of a soap solution is $3 \times 10^{-2} \,N/m$, then the work done in forming a soap film of $20 \,cm \times 5 \,cm$ will be