$A$ mercury drop of radius $1 \,cm$ is sprayed into $10^6$ droplets of equal size. Calculate the energy expended if surface tension of mercury is $435 \times 10^{-3} \,N/m$.

Consider a soap film on a rectangular frame of wire of area $3 \times 3 \,cm^2$. If the area of the soap film is increased to $5 \times 5 \,cm^2$, the work done in the process will be (surface tension of soap solution is $2.5 \times 10^{-2} \,N/m$).

If $\sigma$ is the surface tension,the work done in breaking a big drop of radius $R$ into $n$ drops of equal radius is:

Energy needed in breaking a liquid drop of radius $R$ into $n$ smaller drops,each of radius $r$,is [where $T$ is the surface tension of the liquid].

The work done in blowing a soap bubble of radius $0.2 \, m$,given that the surface tension of the soap solution is $60 \times 10^{-3} \, N/m$,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').