[" 27.A radioactive sample has "8.0times10^(18)" active nuclei at a certain instant.How many of "],[" these nuclei will still be in the active state after two half-lives (in "times10^(18)" )."]

A radioactive sample has 6.0 xx 10^18 active nuclei at a certain instant. How many of these nuclei will still be in the same active state after two half-lives?

A radioactive sample has 6.0 xx 10^18 active nuclei at a certain instant. How many of these nuclei will still be in the same active state after two half-lives?

A radioactive sample has 6.0 xx 10^18 active nuclei at a certain instant. How many of these nuclei will still be in the same active state after two half-lives?

A radioactive sample has 8.0xx10^(18) active nuclei at a certain instant. How many of these nuclei will still be in the active state after two half-life ("in" xx10^(18)) ?

A radioactive sample has 8.0xx10^(18) active nuclei at a certain instant. How many of these nuclei will still be in the active state after two half-life ("in" xx10^(18)) ?

A radioactive sample has 2.0 xx 10^(20) active nuclei at a certain instant of time. How many of them will still be in the same active state after three half-lives?

(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.

A sample of a radioactive substance has 10^(6) radioactive nuclei. Its half life time is 20 s How many nuclei will remain after 10 s ?

A sample of a radioactive substance has 10^(6) radioactive nuclei. Its half life time is 20 s How many nuclei will remain after 10 s ?