Question

The half life of protactinium 234 in its ground state is 6.69 h. What fraction of a given amount remains after 26.76 h

Answer 1

your answer is 1/16

because once you multiply the first two stated numbers you divide it by the last to get your answer

Answer 2

Answer:

¹/₁₆

Step-by-step explanation:

The half-life of Pa-234 (6.69 h) is the time it takes for half the Pa to decay.  

After one half-life, half (50 %) of the original amount will remain.  

After a second half-life, half of that amount (25 %) will remain, and so on.  

We can construct a table as follows:  

  No. of                  Fraction

half-lives   t/(h)   remaining

     2         13.38            ¼    

     3        20.07            ⅛

     4        26.76             ¹/₁₆

     5        33.45             ¹/₃₂

We see that 26.76 h is four half-lives, and the fraction of Pa-234 remaining

is ¹/₁₆.