A pure radioactive substance has a mass of 30 micrograms but had a mass of 240 micrograms 48 years ago. Assuming that the only changes in mass are due to radioactive decay, the half-life of the substance is years. Please choose the correct answer from the following choices, and then select the submit answer button.

Half-life of the substance is 16 years.

Explanation:

Expression for rate law for first order kinetics is given by:

where,

k = rate constant  

t = age of sample  = 48 years

a = initial amount of the reactant = 240 micrograms

a - x = amount left after decay process = 30 microgarms

b) of reaction  

Thus half-life of the substance is 16 years.