49 After decaying for 48 hours, l/16 of the original mass of a radioisotope sample remains unchanged. What is the half-life of this radioisotope?
(1) 3.0 h (3) 12 h(2) 9.6 h (4) 24 h
(1) 3.0 h (3) 12 h(2) 9.6 h (4) 24 h