(a) State the law of radioactive decay. Write the SI unit of 'activity'.
(b) There are radioactive nuclei in a given radioactive sample. If the half life of the sample is 20 s, how many nuclei will decay in 10 s?
(a) Statement : Rate of decay of a given radioactive sample is directly propotional to the total number of undecayed nuclei present in the sample. (1)mark
Unit- becquerel(Bq) (1/2)mark