Question

You have an isotope with a decay constant of 3.33 x 10-3 s -1 . What is the half-life of this isotope? (use correct number of significant figures in your final answer.)

Answer 1

The formula for half-life:   

ln2 = 0.693147 (No. of significant digits = infinite)

decay constant = 3.33*10^-3 0.0333 (No. of significant digits = 3, as the zeros between decimal and number are insignificant)

half-life =   

For division: The LEAST number of significant figures in any number of the problem determines the number of significant figures in the answer

i.e no. of significant digits in answer should be 3

Therefore, half-life = 208s