The unit of surface tension is

Explanation: 

Surface Tension:

• It is defined as force per unit length in the plane of the liquid surface at right angles to either side of an imaginary line drawn to the surface.
• Mathematically, 

\(Surface\;Tension = \frac{{Force}}{{Length}}\)

• It is the tendency of the liquid surface to shrink into a minimum surface area.
• The SI Unit of surface tension is N m-1
• It allows insects to float and slide on the water surface, usually more dense than water
• The molecules at the surface have unbalanced force rather than molecules at deeper and the resultant force moves downward this is surface tension.

Work done in increasing the surface area

We know that, Work (W) = Force (F) × Displacement (d)

∴ W = σ × L × Δx

∴ W = σ × (B × Δx) = σ × (change in Surface Area)

\(\therefore \sigma =\frac{Work}{Change~in~Surface~area}\)

So, from here, The unit of Surface tension is energy per unit area