A penny has copper on the outside and zinc on the inside with a density of about 7.2 g/mL (water is about 1.0 g/mL). Two pennies are dropped in hydrochloric acid. One penny is
brand new and the other has deep scratches on it. The mixture bubbled. The next day, one of the pennies is
floating. Both pennies look the same. Which of the following is a probable explanation for the floatingpenny?

A. The zinc reacted with the hydrochloric acid in a single replacement reaction.
b. The zinc reacted with the hydrochloric acid in a double replacement reaction.
C. The copper reacted with the hydrochloric acid in a single replacement reaction.
d. The copper reacted with the hydrochloric acid in a double replacement reaction.