The half-life of against . Calculate the activity of 1 g sample of . Avogadro’s number is .
None of these
1 gram-atom of has a mass of 238 g and contains atoms. Therefore, the number of atoms in 1g of
The half-life T of
Therefore, the decay constant of
The activity or rate disintegration at any instant, when the number of atoms is N, is
1 milligram radium has . Its half-life is 1620 years. How many radium atoms will disintegrate from 1 milligram of pure radium in 3240 years?
A sample of radioactive substance has 106 radioactive nuclei. Its half-life time is 20 seconds. How many nuclei will remain after 10 seconds?
A sample contains 10–2 kg each of the two substances A and B with half-lives 4 seconds and 8 seconds respectively. Their atomic weights are in the ratio of 1 : 2. Find the amounts of A and B after an interval of 16 seconds.
The half-life of radius is 1600 years. After how many years 25% of a radium block remains undecayed?
The half-life of polonium is 140 days. In what time will 15 g of polonium be disintegrated out of its initial mass of 16 g?
The activity of a radioactive element reduces to th of its original value in 30 years. Find the half-life and the decay constant of the element.
The half-life of thorium-X is 3.64 days. After how many days will 0.1 of the mass of a sample of the substance remain undecayed?
How much of 5.00 gram of polonium will decay in one year? The half-life of polonium is 138 days.
The half-life of a radioactive substance is against . Calculate the decay rate for atoms of the substance.
The half-life of is 28 years. How much is the disintegration rate of 15 mg of this isotope? The Avogadro’s number is .