Radioactive `^138I has a half-life of 8.0 days .A sample containing ``^138I` has activity `20 mu Ci`at t=0.(a) What is its activity at t=4.0 days?(b) What is its decay constant at t=4.0 days?

Radioactive 131I has a half-life of 8.0 days .A sample containing 131I has activity 20 mu Ci at t=0.(a) What is its activity at t=4.0 days?(b) What is its decay constant at t=4.0 days?

Radioactive ""^(131)I has a half-life of 8.0 days. A sample containing ""^(131)I has activity 20mu Ci at t = 0. (a) What is its activity at t = 4.0 days? (b) What is its decay constant at t = 4.0 days?

Radio active phosphorus 32 has a half life of 14 days. A source containing this isotope has an initial activity of 10 m Ci. (i) What is the activity of the source after 42 days? (ii) What time elapses before the activity of the source falls to 2.5 mCi?

(a) A radioactive sample has 6.0 xx 10^(18) active nuclei at a certain instant. How many of these nuclei will still be the same active state after two half-lives? (b) Radioactive phosphours -32 has a half-life of 14 days. A source containing this isotope has an initial activity of 10muCi . (i) What is the activity of the source after 42 days? (ii) What time elapse before the activity of the source falls at 2.5muCi ? (c) 1g of a radioactive substance disintergrates at the rate of 3.7 xx 10^(10) dps . The atomis mass of the substance is 226 . Calculate its mean life.

Half life of ""^(131)I is 8 days. Sample has an activity 6.4 mCi at a certain time. What is the activity 40 days later?

A radioactive sample with half-life 2 days has initial activity 32mu Ci . What will be its activity after 8 days?

Half-life of a radioactive sample is 200 days. Its decay constant is

A radioactive substance has a half-life of 64.8 h. A sample containing this isotope has an initial activity (t=0) of 40muCi . Calculate the number of nuclei that decay in the time interval between t_1=10.0h and t_2=12.0h .

A radioactive substance has a half-life of 64.8 h. A sample containing this isotope has an initial activity (t=0) of 40muCi . Calculate the number of nuclei that decay in the time interval between t_1=10.0h and t_2=12.0h .