A rock contains 0.153 mg of lead-206 for each milligram of ...

[itsmyluck]

A rock contains 0.153 mg of lead-206 for each milligram of uranium-238. The half-life for the decay of uranium-238 to lead-206 is 4.5  109 yr. The rock was formed ________ years ago.
 
  A) 6.89  108
  B) 5.60  108
  C) 7.33  108
  D) 1.06  109
  E) 8.08  108

Question 2

The concentration of sodium sulfate solution is 18.6 by mass. There are ________ g of sodium sulfate present in a 236.5 g sample of this solution.
 
  A) 44.0
  B) 4400
  C) 0.000786
  D) 7.86
  E) 1270

[TheDev123]

Answer to Question 1

D

Answer to Question 2

A

[itsmyluck]

Both answers were spot on, thank you once again

[TheDev123]

Great! Please up vote