If one starts with one curie of radioactive substance of half – life  12 hr’s , the activity left after a period of 1 week will be

Given : Time =1 week= 7 days = 7 x24 hr’s  No. of half lives=n=tT1/2=7×2412=14  Deacy Law, A=Ao12n=1×1214=116384=61×10−6=61 micro-curie