The half-life of ²¹⁵ At is 100 ~s . The time taken for the radioactivity of a sample of this nucleus to decay to 1 16 th of its initial value is

Step-by-step solution

Activity, ( R R₀ )= ( 1 2 )^n 1 16 = ( 1 2 )^n array ll & ( 1 2 )^4= ( 1 2 )^n & n=4 array t T =4 [ n= t T ] t=4 T=4 100 ~s t=400 ~s