The activity of a freshly prepared radioactive sample is `10^(10)` disintergrations per second, whose mean life is `10^(9)s`. The mass of an atom of this radioisotope is `10^(-25) kg`. The mass ( in `mg`) of the radioactive samples is

The activity of a radioactive nucleide (X^(100)) is 6.023 curie. If its disintegration constant is 3.7xx10^(10) "sec"^(-1) , the mass of X is

If the half-life of a radioactive sample is 10 hours its mean life is

A freshly prepared smaple contains 16xx10^(20) raadioactive nuclei, whose mean life is 10^(10) seconds The acitiivity of the sample just after 4 ahlr lives time is

The activity of a sample of radioactive element .^(100)A is 6.02 curie. Its decay constant is 3.7 xx 10^(4) s^(-1) . The initial mass of the sample will be:

Calculate the number of disintegrations per second of 1 g of a radioactive sample whose half-life is 1.4 xx 10^(16)s . The mass number of the sample is 238

A radio active sample contains 10^(6) radioactive nucleus it s half life is 20 sec . Number of remaining nucleus after 10 seconds.

The specific activity of a preparation consisting of radioactive Co^(58) and non-radioactive Co^(59) is equal to 2.2xx10^(12) disintergration per sec gram. The half-life of Co^(58) os 71.3 days. The ratio of the mass of radioactive cobalt in that prepartaion to the total mass of the prepartion in percentage is

Initial active mass of a radioactive sample is 76 gm . The active mass at the end of two mean lives is approximately.

How many atoms decay in one mean life time of a radioactive sample-

Radioactivity of a radioactive element remains 1//10 of the original radioactivity after 2.303 seconds. The half life period is