How much does 100 nickels weigh?

Assuming "100" means "$100", there are 20 nickels in a dollar so $100 is 2000 nickels.

US nickels weigh 5 gm so 2000 of them weigh 5*2000 = 10,000 gm, or 10 kg.

Current Canadian nickels weigh 3.95 gm so 2000 of them weigh 3.95*2000 = 7900 gm, or 7.9 kg.