If the level of 67Ha in recent sediment is 0.80 Bq per gram, and a sample of older sedimentary rock shows a Bq level of 0.20 Bq per gram. How old is the sedimentary rock?

Which of the following may one conclude from a map that shows the average ph value of rainfall in the u. s.? acid rain is a more serious problem on the east coast. acid rain falls equivalently across the continental u. s. there are more factories on the west coast. the midwest has fewer forests than the rest of the u. s.