40K decays to 40Ar with a half-life of 1.27 x109 years.  The age of a mineral sample that has a mass ratio of 40Ar  to 40K of 0.812 is ___   years. 1.56 × 10 9 1.09 × 10 9 7.55 × 10 8 1.02 × 10 9 1.47 x 10 9

Iodine-131 is a radioactive isotope. After 6.00 days, 59.6% of a sample of 13I remains. What is the half-life of 1311? days TOOLS x10

The radioactive isotope 212pb has a half-life of 10.64 h. A sample containing this isotope has an initial activity (t = 0) of 55.0 pCi. Calculate the number of nuclei that decay in tl time interval between t, = 7.0 h and t, = 15.0 h. nuclei

Macmillan l 30: F2 W S A 210.2 ng sample of an unknown radioactive substance was placed in storage and its mass measured periodically. After 47 days the amount of radioactive substance had decreased to 26.28 ng. How many half-lives of the unknown radioactive substance have occurred? number of half-lives: #3 H 80 F3 mmand E D A GA $ X C 4 OOD 886 F4 R F % от ото 5 V F5 T G ^ 6 B F6 Y & 7 H 8 F7 U N 00 * 8 DII FB J L - ( 9 M K DD F9 O . V - ... I 4 F11 { [ option + = ? 11 1 F12 } ] half-lives delete return st

A sample of bone is subjected to radiocarbon dating. The current decay rate observed for its carbon-14 content is 11.2 disintegrations per minute per gram of carbon. What is the age (in years) of the bone? The half-life for carbon-14 is 5.73 x 103 yrs, and the decay rate for carbon-14 in living organisms is 14.3 disintegrations per minute per gram of carbon.

14C is a radioactive isotope that is used to measure objects' ages by determining how much ¹4C has not yet decayed. ¹4C has a half-life of 5730 years. If the ¹4C content of a piece of wood is 2% of the original amount, how old is it? 5.2 × 104 y 2.2 × 104 y 2.2 × 105 y 3.2 × 104 y X