9514 1404 393
Answer:
30 grams
Step-by-step explanation:
The time 120 seconds is 4 times the half-life of 30 seconds. That means (1/2)^4 = 1/16 of the original amount will remain. That is (480 g)(1/16) = 30 g.
30 g of the radioactive rhodium will be left
