A mercury drop of radius \( 10^{-3} \, \text{m} \) is broken into \( 125 \) equal size droplets. Surface tension of mercury is \( 0.45 \, \text{N m}^{-1} \). The gain in surface energy is:
\( 17.5 \times 10^{-5} \, \text{J} \)
\( 5 \times 10^{-5} \, \text{J} \)
\( 28 \times 10^{-5} \, \text{J} \)
\( 2.26 \times 10^{-5} \, \text{J} \)