Question

what did the vinegar do to the pennies? made them feel rough made them shiny oxidized them, causing them to rust quickly oxidized them, making it cleaner

Explanation:

Vinegar is an acid. When pennies (made of copper) are placed in vinegar, the acid in the vinegar reacts with the copper - oxide layer on the pennies. This reaction removes the copper - oxide layer, revealing the shiny copper underneath.

Answer:

made them shiny