A radio active material is reduced to 1 8 of its original amount in 3 days. If 8 × 10 - 3 kg of the material is left after 5 days the initial amount of the material is

Step-by-step solution

The initial and final amount of the radioactive substance are related by the formula N N 0 = 1 2 n       . . . 1 where, n is the number of half lives. Substitute 1 8 for N N 0 into equation (1) and solve to calculate the value of n . 1 8 = 1 2 n ⇒ 1 2 3 = 1 2 n ⇒ n = 3 The half-life of the radioactive element can be calculated as follows: t t 1 2 = n       . . . 2 Substitute the values of the known parameters into equation (2) and solve to calculate the half-life. 3