Copper doesn't rust
If they are an alloy, they will eventually rust.
How long will it t take a quarter to rust in fresh water
a long time
It depends on the quality of the nail. If it is painted it Amy take long to rust. In general it may take a month or so for the nail to rust.
Modern coins cannot rust, as they are not made of iron.
a week it take or two
5 months
50 years
If they were, they would rust too easily from the water vapor in the atmosphere and the oils from our fingers and be useless as they would not last long. Copper, nickel, silver and gold have become the metals of choice for coins as they resist rust.
Cannot rust. No oxygen or water.
For a coin to rust, it would have to be made of iron. Silver coins tarnish and copper coins get corroded when they are left out in the air and moisture.