Pennies are made of copper-plated zinc. Copper is a metal that reacts with oxygen in the air to form a layer of copper oxide, which is what gives pennies their characteristic brown color. When pennies are placed in water, the water can dissolve some of the copper oxide, causing the penny to turn a brighter shade of copper. However, pennies will not rust in water because zinc is a metal that does not react with oxygen in the air to form a layer of rust.

Pennies in Vinegar:

Vinegar is a mild acid that can react with the copper oxide on pennies to dissolve it. This will cause the penny to turn a bright copper color. However, pennies will not rust in vinegar because zinc is a metal that does not react with acids to form rust.

Pennies in Bleach:

Bleach is a strong oxidizing agent that can react with the copper oxide on pennies to dissolve it. This will cause the penny to turn a bright copper color. However, pennies will not rust in bleach because zinc is a metal that does not react with oxidizing agents to form rust.

Conclusion:

Pennies will not rust in water, vinegar, or bleach. This is because zinc is a metal that does not react with oxygen, acids, or oxidizing agents to form rust.