A spherical drop of water has radius I mm If surface tension of water is $70 \times {10}^{-3}$ N/m difference of pressures between inside and out side of the spherical drop is

• A

  35 $\mathrm{N}/{\mathrm{m}}^2$

• B

  70 $\mathrm{N}/{\mathrm{m}}^2$

• C

  140 $\mathrm{N}/{\mathrm{m}}^2$

• D

  Zero