Unit of surface tension in S.I. unit is

ANS:B - Joule/m²

Surface tension is not typically measured in joules per square meter (J/m^2), as joules per square meter represent energy per unit area, which is not directly applicable to surface tension. Surface tension is the force acting per unit length along the interface between two immiscible fluids or along the surface of a liquid. Therefore, its unit is expressed in terms of force per unit length, which in the International System of Units (SI) is Newton per meter (N/m). The unit N/m represents the amount of force (in Newtons) required to stretch or deform a surface by a unit length (in meters), indicating the strength of the cohesive forces acting within the liquid. Joule per square meter (J/m^2) is a unit of energy per unit area and is commonly used to measure quantities such as energy density or surface energy. While surface tension does involve energy considerations, it is more accurately described in terms of force per unit length rather than energy per unit area. Therefore, joules per square meter is not the typical unit used to express surface tension.