Question

Why does adding SALT to water increase it's surface tension?

Answer 1

the salt, when dissolved in water, adds an ionic component to the surface structure.
When one examines pure water, the surface is a mesh where the hydrogens of each molecule are weakly attracted to the oxygens of the neighboring molecules.
So, when you add salt to water, it separates, and you get "rings" of water molecules around each ion.

Answer 2

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