The mass of an object changes from 0.002 g to 0.00025 g in a time period of 1500 years.The half-life of the object is

Options

(a) 500 yrs
(b) 850 yrs
(c) 700 yrs
(d) 1000 yrs

Correct Answer:

500 yrs

Explanation:

Here, N₀ = 0.002 g, N = 0.00025 g. t = 1500 years.
Now , k = 2.303 / t log N₀ / N = 2.303 / 1500 log (0.002 / 0.00025).
t (1/2) = 0.6993 / k = 500 years.