What is the half-life of 20 g of a radioactive sample if 5 g remain after 8 minutes? Chemistry Nuclear Chemistry Nuclear Half-Life Calculations 1 Answer Sam May 31, 2016 #4 min.# Explanation: #m_i=m_rxx2^n# #m_i=" is the initial mass"# #m_r=" is the remaining mass after n periods"# # n " is the number of periods "# #2^n=m_i/m_r# #2^n=20/5# #2^n=4# #2^n=2^2 " "=> n=2# #n=(time)/("half-life")# #"half-life "= (time)/n# #"half-life" =( 8 min)/2 = 4 min# #20 \ g -> 10 \ g -> 5 \ g# Answer link Related questions How do you calculate nuclear half life? Question #b61f8 Question #406c5 What is the half-life of a radioisotope if 1/16 of it remains undecayed after 26.4 days? If a radioactive Isotope has a half life of 30 days then how long will it take 1000 grams to decay ... If the half life of an unstable element is 5000 years, what percentage of the parent material will ... How much material will be left if a radioactive isotope has a half life of 1.3 billion years in 3.9 ... Can you determine the annual decay rate of a certain radioactive isotope that has a half life of ... If 100.0 g of a radioactive isotope that has a half life of 25 years, identify the amount of that ... How many minutes will it take for an isotope that has a half life of 45 minutes to decay to 1/8th ... See all questions in Nuclear Half-Life Calculations Impact of this question 1937 views around the world You can reuse this answer Creative Commons License