Atoms and Nucle...

For a substance the average life for a-emission is 1620 years and for β emission is 405 years. After how much time the 1/4 of material remains after α and β emission

The half-life of radioactive Polonium (Po) is 138.6 days. For ten lakh Polonium atoms, the number of disintegrations in 24 hours is

A and B are two radioactive substances whose half lives are 1 and 2 years respectively. Initially 10 g of A and 1 g of B is taken. The time (approximate) after which they will have same quantity remaining is

Half life of a radio-active substance is 20 minutes. The time between 20% and 80% decay will be

After 280 days, the activity of a radioactive sample is 6000 dps. The activity reduces to 3000 dps after another 140 days. The initial activity of the sample in dps is

Excitation energy of a hydrogen like ion in its first excitation state is 40.8 eV. Energy needed to remove the electron from the ion in ground state is

The rate of disintegration was observed to be 10¹⁷ disintegrations per sec when its half life period is 1445 years. The original number of particles are

An atomic power nuclear reactor can deliver 300 MW. The energy released due to fission of each nucleus of uranium atom U²³⁸ is 170 MeV. The number of uranium atoms fissioned per hour will be

A hydrogen like atom of atomic number Z is in an excited state of quantum number 2n. It can emit a maximum energy photon of 204 eV. If it makes a transition to quantum state n, a photon of energy 40.8 eV is emitted. The value of n will be

A radioactive sample is α–emitter with half life 138.6 days is observed by a student to have 2000 disintegration/s. The number of radioactive nuclei for given activity are