The half-life of the radioisotope 158Eu is 0.77 h. How much time is required for a 160.0-g sample of 158Eu to decay to 2.07 g? a. 3.0 h
b. 4.0 h
c. 6.0 h
d. 2.1 h
e. 4.8 h

e. 4.8 h

Explanation:

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

where,

k = rate constant  

t = age of sample

a = let initial amount of the reactant  

a - x = amount left after decay process  

a) for rate constant

Half life is the amount of time taken by a radioactive material to decay to half of its original value.

b) for 160.0 g to decay to 2.07 g

The time  required for a 160.0-g sample of 158Eu to decay to 2.07 g is 4.8 hours

answer; ///(d) the correct answer is double or triple

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