what is the effect of solute on the surface tension of liquid?

what is the effect of impurities on the surface tension of liquid.

What is the effect of temperature on the surface tension of a liquid ?

What is the effect of temperature on surface tension and viscosity?

If temperature increases, the surface tension of a liquid

Which of the following does not affect surface tension of liquid?

Surface tension of a liquid is a molecular phenomenon of liquids involving the force of cohension along the liquid molecules. It is scalar quantity and is numberically equal to the surface energy. Numerically, it is proved that the potential soluble salts and surfce active substance. Sparingly soluble salts and surface acitve substances decrease the surface tension of the liquid. However, the fairly soluble solutes increase the surface tension of the liquid. Surface tension of a liquid is independent of surface area but it depends on the intemolecular forces and the temperature. Which among the following is not the unit of surface tension ?