A Sample of Phosphorus-32 Is Found to Have an Activity

Multiple Choice

A sample of phosphorus-32 is found to have an activity of 885 disintegrations per hour (dph) .After 25 hours the activity has decreased to 841 dph.What is the rate constant for the decay of phosphorus-32?

A) 0.0038 hr^-1
B) 0.0020 hr^-1
C) 0.15 hr^-1
D) 490 hr^-1
E) 0.12 hr^-1