It is not that difficult to tell if a high-purity silver coin is real. They have certain wear characteristic you get to know when you deal with them enough. It is the low-purity ones that are difficult to prove - like 50% silver English coins 1920-46. They go grey and they aren't very heavy. Anything 90% or over is easy to tell simply by colour and weight. If things get that bad, they will be taking anything of value; foreign notes, silver coins, grand pianos, sacks of potatoes. Silver coins are a very convenient size for every day transactions - who wants to go buy food and expect them to make change from a $1550 krugerrand? A $35 one ounce coin like a silver eagle is much easier, and at 99.9% pure they may scratch easily but are also easy to cut into halves and quarters, or to cut a quarter into two bits.

Yes, and this so called decay function really means the issuer giving themselves a continues pot of money to spend - with all the problems that causes. Not least, transferring real resources to someone lucky enough to have their hand in the money pot instead of making some useful good to sell. Undermines the division of labour and causes shortages.

There is no point in saving something you don't ever spend. All bitcoins now hoarded will come back on the market eventually. Same with any currency or trade-commodity.

Nope. You had the Great Depression when Roosevelt seized all the gold and took the dollar off the gold standard in 1933, at least internally. Unsurprisingly this had the effect of impoverishing your country until about 1946, at least compared to what it was up to the 1920s.

Wanna bet? Ever tried to buy a Zim Dollar? Funnily enough, they aren't available any more. If you want some it costs you really money to have someone ship it to you in a bad, but what you get is still worth nothing and not even accepted by the Zim central bank anymore. That is amounts to a negative value as I see it.

Compelling debtors to pay is surely about getting them to pay what they have agreed to. It doesn't matter what currency the contract was negotiated it, only that they pay the stated amount. Therefore anything uniform, divisible, scarce and valuable enough to be a portable store of value, can be used as money.

They are currently accepted by all merchants. Don't save them though, because these days they have an expiry date. There is an awful lot of inflation just over the horizon.

Pieces of eight is the English name for a Peso, which is 1/8th of a Spanish silver dollar. Literally, you cut the Spanish dollar in eight slices like a pizza. It is the best way to get paid because it is silver, and that is the only currency of durable value listed as a option to the quiz. Silver is better than gold for money as there is more of it, so you can use it for meaningful transactions. There just isn't enough gold for it to be the main money. The rest you can forget. Ten years from now most of them won't be worth the paper they are printed on.