Question

old pennies become dull when the copper on the outside combines with oxygen in the air. this can take many years. the result is a new chemical called copper oxide. when you put pennies into a vinegar and salt solution, the acetic acid and salt work together. they dissolve the copper oxide. it becomes part of the solution. when you put steel paper clips in the solution, some of the iron in the steel dissolves as well. the copper in the solution and the iron that’s left in the paper clip are strongly attracted to each other. so the copper ends up sticking to the paper clip. and that’s how you use chemistry to make copper - plated paper clips! fill in the blanks to explain why the experiment works when you follow the steps. the pennies become dropdown: old, shiny, dull because the mixture of vinegar dissolves cop... the paper clips get a cop... because the leftover copper in the solution sticks to the dropdown in the paper clips.

Explanation:

• For the first blank: The text says vinegar - salt solution dissolves copper oxide (which makes pennies dull), so pennies become shiny as the dull - making copper oxide is removed.
• For the second blank: The text states that iron in steel paper clips dissolves, and copper in solution is attracted to the leftover iron in the paper clips, so copper sticks to the iron in the paper clips.

Answer:

First blank: shiny; Second blank: iron